Ron, if you are stripping down an 85 Riviera engine and are not keeping the hot air and Riviera parts, sell them in the parts for sale forum, while not worth as much as IC parts, they will sell. The turbo, exhaust manifolds/crossover, oil pan, oil pick up, motor mount are unique to the Rivieras and getting hard to come by. Do you have the transmission an differential also?
I am just about done collecting parts to do the conversion of same 85 Riviera engine mounted on stand, had to change everything except block, heads and timing cover, you should have it easy just transfer your parts over. Keep all your bolts in order from the 87 engine, while some 85 bolts are same and all metric, the 87 brackets, manifold,headers,etc. will bolt up with the right lengths without guesswork. Have to use 87 valve covers and dipstick tube and dipstick, fuel lines to rail too. Oh, at least the knock sensor is the same, what a break!
Eric, anything good or bad about the Riviera cam? Probably should just change it along with timing chain and see what cam the IC guys are using with there mods.