340 intake manifold

hey all: I'm thinking about going with the original manifold on this 340 but I have some questions. First it's a 71 and it has a 5/16 hole on the drivers side just behind the thermostat opening, between there and the carb. No threads just a hole?! I've looked at other pix and others have it and nothing in it. The question is; is something s'posed to be there?

Also it's got a spot for an old choke stove which I don't plan on using. It doesn't go anywhere but I have seen caps to put over it. Do I need a topper? Anybody ever have trouble with carb clearance (manual choke 650 DP) w or w/o the topper.

Finally, aftermarket intakes (well my old one anyway) had an extra hole near the thermastat for ??? whatever but mine had a equus sensor in it for the mechanical type temp gauge. Anybody know if theres an adaptor for the old original electrical sensor to make this work? how bout a Y where the heater plugs in?

I have a bunch of questions about water pump plumbing but that is a different thread I think

thanks again all! and happy Memorial Day btw

LAP