Hey
welcome to the boards
model changes... now you have a tricky one there hehe.. there are quite a few model differences..
ma70 chassis is 7mge/7mgte = 3lt non turbo or 3lt single turbo
ga70 chassis is 1ggeu/1ggte = 2lt non turbo or 2lt twin turbo
86 in the US is always non turbo... it has black/dark grey moulding with i think 4 like stripes which are a light grey, the windscreen jet washers are only about 5mm long and quite roundish compared to 87's which have longer ones and a little more squared
also on the dashboard you should have the rear demister, hazard switch, and parklight switch... if you don't have a parklight switch then you either have an 87 or an 88
now to tell an 87 from an 88 is also in the washer jets as they will be different... 88's will be the same as 86 short stubby ones
the moulding is totally different to any other model.. it's quite hard to explain but well.. on other models if you run your finger over the moulding you will feel the pattern... 87's have perfectly smooth moulding and the pattern is inside where the like clear cover moulds over it.. if that made sense at all hehe
87's are widebody.. guards flare out more than the others, aero roof (lift out roof) have a coin slot in replacement of the park light switch
the supra you saw was an 89+ supra... they had steering wheel changes in that year... if that supra is still at the junkyard see if you can get the loom that was plugged into the indicators.. that is what runs the cruise control etc... but unfortunately i don't have a wiring diagram for all of that
the 89+ had different indicator switches... smoother than the older ones
diff steering wheel
i believe burgundy interior was abolished?
the turbo variant from 89+ is 2hp more than the 86-88
they had two coin slots on the dash as cruise control on switches were moved to the steering wheel where earlier ones had the "on" switch on the dash then set cruise and cancel on the steering wheel
the bumpers and taillights were changed in 89.. quite a popular thing to do is upgrade to the later lights
and of course they added the great cup holder lol... although how you stop the center console smashing your straw to bits i'm not sure yet hehe
there's most of it i think... well the obvious anyway
rust in some ways is common... usually the bottom trim or the rear wiper blade bolts leak and let water into the boot so you end up with a rusty spare wheel well... in some cases the side pockets where the jack and tools are stored end up goldfish ponds hehe...
check under the boot rubbers for rust and make sure your taillights are still sealed well
ahh bugger bout the engine
how much money have you got to spend on her... maybe do the 7mgte swap? or keep it in mind for the future
i would take the cams and caps to the reconditioner as well and get them polished up... it can be oil starvation or the engine getting extremely hot... heavy scoring is from crap being in the oil... possibly ran a big end (rod end) at some stage and some shavings were left in the engine or just plain didn't get oil changes often.. who knows... i would go towards neglect anyway
yup head gaskets are a problem but not because the engine was designed poorly but really you gotta blame the mechanics... you've got it in a nutshell tho... either arp head studs or brand new toyota head bolts and torque em down to 75ft lbs and you should be away laughing... i would definitely suggest a metal head gasket.. if you do the metal head gasket it is imperative that you get the block prepped for it as well... so you may as well do just a good ol rebuild... main bearings, big end bearings, rings, get ya pistons cleaned up, block face cleaned/skimmed for metal head gasket, and make sure you head isn't warped and get her skimmed and leak tested all at the same time... you reconditioner should be able to tell you whats important to be done for a mhg
you can get metal head gaskets from alot of companies i.e. mvpmotorsports.com, suprasport.com, 935motorsports.com, horsepowerfreaks.com or just go to say the hks website and find your nearest dealer
you should be able to get ARP head studs from the same companies above
now the manual... i'm not sure how common they are there but your best bet would be to find an R154.. you can bolt that up later on behind the 7mgte and she'll handle a wack of power
but you can just bolt up a w58 or any w series gearbox
things i would also suggest you do since ur engine packed a sad is get your radiator flushed by a radiator company.. to ensure its been flushed properly... new thermostat, new radiator cap, new water pump, replace any very soft or very hard hoses on your engine and you shouldn't have any overheating problems
there have been numerous counts of overheating with the 7m series engine but that is due to things not being replaced or blocked or old or leaking
umm really other than that i can't really think of any other things
good luck with your car