performance parts swap

[HINsupra88]

hey everyone i had a question im not to familiar with how long parts last and what not now lets say i wanted to drop in a new engine and trans in my 1988 toyota supra but i already have exspensive gear under the hood example a whole new turbo upgrade kit intercooler cam shafts u kno basicaly the typical stuff and it all has a lil less then 40,000 miles on them now when i swap engines and trans would all those parts be workin up to par with my new engine and trans or are those parts bad? do they ever go bad? and can someone just give me general advice on what is good and bad to get installed in a supra performance wise?

-joe