I've got an 87 350 engine I'm building, and I wasn't aware of the different bolt angle of the 4 screws in the center of the intake manifold. The engine is a TBI, that I'm converting to a carb'd engine (for some reason???). None of the SBC intakes I have would bolt to the heads. I thought about drilling out the 4 bolt holes on intake manifold, but I didn't want to screw any of them up...
Then I made a plate that would accept a 4Bbl, carb, and adapt the the 3 bold configuration of the TBI intake manifold, but sealing it, or keeping it sealed, became an issue,.
Today, I purchased a Weiand 4Bbl intake for 87-94 SBC's from Summit. It's a stock 1987 Truck 350 engine with 87K miles on it. just didn't feel like screwing around with TBI, in my 68 GMC, but had no idea carb'ing it would bring so many obstacles. You're never tyoo old to learn, I suppose.
This is a temporary engine I'm building so that I can pull the 355 out of my truck and rebuild it, again. I just didn't want to side line the truck while re-building, and probably de-tuning my "A" engine. lol
So, we'll see.