what year is your lt1. mine is a '95 and has the vented optispark. those are supposed to be much better for keeping moisture out. the only way i've heard to convert is to run a carb and distrib goes through the normal spot at the rear of the intake manifold. don't know if you can mod the stock manifold to take a older distrib. there is the drive for the oil pump back there, but it uses a shaft that doesn't come up out of the manifold. what is the reason you want to swap it?
'77FJ40 "Bionic" LT1, 4L60E, NP208, 14B/Detroit, D60/ARB, 4.56's, SOA/FJ55 rears, SR, 96"wb
'63 FJ45 SB
'69 FJ40 Trailer
'97 F350 PSD CC 4X4