Updating this to maybe help someone else.
My trans took a crap, so I was dealing with that.
Now that the trans issue appears fixed, I was able to verify the hot start issue is fixed.
I replaced the CCA (copper clad aluminium) wires with 00awg copper and that fixed the issue.
I now measure a 2V improvement in voltage drop when cranking the motor (9.5V vs 7.5V).
Not sure why it was only an issue when hot, but the pure copper wire works.
I guess there's a reason the CCA wire is 1/2 the price........ Glad you've got it fixed.  Just for info, if your starter motor has permanent magnets fitted (many do), they lose magnetism when hot and won't make as much torque with the same current flowing. Can't be helped it's just physics.
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials.
9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge.
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
| 
