I had some issue with a few "built" 440s.

What I ended up finding out, bigger battery cable from trunk to starter is required, go bigger than the kits suggest. Get a bigger battery and make sure your grounds are good.

Once these were issues remedied 3 large CI engines crank like low compression small blocks!!! Timing retard and igntion kill not needed then. If weight isnt a huge issue, i got the biggest truck battery i could get. The last one from NAPA had over 1000 CCAs.