Picked up some fresh pump 91 and pulled it a few more times. Current new bests are 570 hp and 556 ft/lbs. I haven't found the sweet spot with timing yet --I think it wants 2 degrees more.

I have to find best timing, add the mufflers, play with lifter pre load and try a .5" spacer.

So far it's pretty stout for a 10.3 comp small block. It has almost 460 ft/lbs @ 2500 rpm but has a bit of lull in the curve, I'm hoping the mufflers help this some. J.Rob