I don't know much about the manifold. It has "JOHNSON" and a part number that might be General Motors issue cast into it. I found it on eBay. Supposedly a propane intake. I modified for 2 barrel Rochester, hot water, and the tapered transition into the head.
Lumps are modified tlowe parts. They are attached with the scab plates you see in the photo instead of a cap screw up from the deck surface. 3/8 inch tall at the gasket instead of tapered to nothing. I was shooting for constant cross section area from the manifold corner to the valves. I know I took more photos but can't find them. I'll post them if I do.
