630 casting 400 block. Compression should end up around 11:1. No flow sheets yet on heads. Heads were down by Muscle Motors for a Top Dragster . Motor made a touch over 1000 with a 604. Softening chamber?
OVER 1000 with a stock block? be very careful with nitrous on it. Sounds a little optimistic to me, but im sure its possible just don't see how its going to live long that's all. IF you putting a healthy dose of nitrous on it, Single digit timing is where id start, but you didn't give any nitrous PPH numbers so im only speculating here.
Google Chamber Softening and im sure you will see whats involved. Basically it lays the chamber back and slows the flame front, allow more timing to be run or at least not be so timing sensitive for heads with small chambers like a B1
