Steve,
Depending on what year LT1 you have can make a difference. I may be a bit off on the years but I believe its all possible. LT1 blocks up to 86 had straight in center bolts. 87 to 95 had the two center bolts angled in. After 95 GM went to the Vortec engine. All of the manifolds are available through major companies. I looked into the Edelbrock catalog and found manifolds for all years. I wish I could claim to know this myself. I read your note and drove down to Nutter Racing. They build engines and heads for Nascar. They helped me through this question. I have a 485 HP 454 BBC in my LA Exotic Cobra. It is built up to where its more power then I need and still runs on pump gas. I have had many problems with mainly Cooling, Cam Problems, fuel fouling plugs etc. I have worked out 95% of the problems by myself. The rest of the time I ask for advice. I hope I helped you out a bit. If you have any questions, ask. If I don't know, I'll ask.
Tom Miletich
