Couldnt be any harder than the sr20det conversion I am doing on my MGB...
Everything in this car is custom...rear end...motor mounts...trans crossmember...turbo manifold...down pipe...harness...
I guess it all depends on what you want to do. The original B series engine would not make the hp the sr20det could period. If I was you I would buy one of these fully built partouts you see laying around. It would be a lot cheaper in the long run