Glad to see you back. Wondered where you disappeared to. She sure took a beating alright. What a shame it tore up the block. I feel your pain. My '78 racecar melted 2 JE pistons testing a new carb but somehow didn't blow the Cometics! I'm gonna do the same thing and put together a stock bottom...
I had a GN with an intermittant stalling problem after driving a while that turned out to be a bad fuel pump relay. It would shut off like you turned the key off with no sputtering. Once it stalled, it would take several minutes to refire (I assume because the relay had to cool down). You need...
Do you mean the thermostat housing? The Motorad CH4853 works on those intakes. There needs to be a gasket under that top plate. You can use one for a Holley Dominator carb and drill the other 2 bolt holes. The opening is the same size.
The Weiand intake in the picture is missing the top plate that the carb mounts to. When they were initially released, different top plates with different mounting patterns were available depending on what type of carb you wanted to use. The groove you are asking about is part of the EGR designed...
You could delete that EGR valve and make block off plates for the intake manifold and the plenum out of steel or aluminum. You'll probably have to make your own gasket or use high temp sealer.
I think the 1980 turbo intake manifold is nearly identical to the '78-'79 except it is aluminum. If that is the case, I might have some of those pieces from an earlier engine. No wiring though.
A .60 compressor housing would be much better than the .42. But the Riviera housing presents as many fabrication problems to adapt as the '84 to '87 housing does. It could be done. But I haven't found a really clean way of adapting any of them without it looking like a hack job. Although the 301...