crab cap ?
you might need a "crab" Distributor cap, My jeepster is on a Blazer chassis. It has had the original 4 cyl, 374 buick nailhead, 401 nailhead, SBC, Small block ford, and now the SB chevy again, , Somewhere along the line I had to cut out a hole in the firewall and build a recessed box and weld it in for GM distributor clearance, In My T bucket SBC I am using a Mallory dual points distributor with a "crab" dist cap. 4 wires come out each side of the dist cap. that style gives more clearance for 2 4 manifold carbs or blowers. I think I first had it when I had a 2 4 cross ram manifold. With that manifold the distributor had to be in the manifold and all go down on the engine at the same time.
To replace the distributor there should be a Wiki article, , batt cable off, remove the dist cap note which way the rotor points,, as you lift the distributor shaft will rotate a little bit because of the spiral gear, note which way it points when you get it all the way up, that is the way you need it to point as you put in the distributor in and it needs to point to the original direction when you get it all the way down, Changing to a points Distributor will require new wiring to match what you use, original points, ? after market points elimination kit? etc.