I bet compression is 10-10.5 that is why you can not run more timing. It will want 40 total. A compression test will tell you if you got too much dynamic compression.

The 750 eddy seems to me to work good on a stone stock BB, when the motor is moded is when they seem to be un tune-able.

I think the oarnge box could be the problem, my 68 dart would just lay over around 3000 rpm with it, put in a parts store generic one after the orange one quit completely and it pulled hard to 5000. Just a couple weeks back a friend brought in his valiant 318 low compression motor with an orange box and wanted me to help him tune it just a bit and timing was jumping all over around 3000 when I tried to set the total timing, swapped in an ancient mallory box and timing was steady as a rock after that, he did not report back about drivability but the big burnout he did when he left makes me think the tune did him some good, would not turn a tire before.