I've got similar dramas at present with the motor for the FED.
I had the crank in and torqued, then realised I could not get a sump to suit the girdle. Cut the girdle down, so it had to be tunnel honed again. In taking the bearings out I could not get them to budge. I got ham-fisted tapping them out, and put a poofteenth of a lip on the edges I tapped.
Should probably have just filed back that lip, but thought I would be cute and put new bearings in.
Honed, new bearings, check mains clearance with plastigauge. 5 thou at the balancer, 3 thou, 4 thou, 5 thou at the flywheel.

Factory spec is 0.8-3.4 thou. Drag cars can run somewhat looser, and for a grey crank diameter 2-3 thou would be considered "loose".
Try rocking the crank fore and aft, stuff-all end float.
Spoke to the machinist. Suspect the King bearings I used are not up to par - not unheard of for them, and ACL reccomened instead.

The King bearings are also made to suit cranks where the thrust face has been machined back, so are oversized for a virgin thrust face. He is not over happy with plastigauge either - OK for a rough out, but should be done with a bore gauge.
Back to the shop when I get a chance, check, mebbe new bearings. This damn thing needs wingnuts or velcro on it given how many times it is being made and unmade.
Cheers,
Harv
327 Chev EK wagon, original EK ute for Number 1 Daughter, an FB sedan meth monster project and a BB/MD grey motored FED.