hard cranking after warm

Does this have stock 318 pistons? If so, then high compression is not the problem.

Battery up front? Cables and connections are suspects. Clena all connections to a bright clean, including the battery cable direct to the block. It appears that you have eliminated the problem of a dragging starter with the new unit.

Check the battery voltage with a known accurate voltmeter when the car is at a fast idle. It should be around 14.0 V + or -. This will say if you charging system is up to snuff.