Big block timing question

Initial and total are not related.

It might take more than normal total, but, sneak up on that number. Open chamber BB's have been run with 38+ total. so it's not unusual. Run it at the track and keep stepping on it. It'll slow down MPH wise when you've gone too far. Check the plugs if you start getting above 38 would be my suggestion. Look for signs of detonation.

If it starts OK at 30, limit it so you hit a decent total number. Run it and find out.