I have a 400 just put together, the core trans had a bad case and frt pump found another case and 895 pump.using hughes RPMV body and a direct drum from a 4l80 with good sprag.trans installed all forward gears wrk great but i need to bring rpm up to get it to go into reverse.at first once it was in reverse it felt fine but after 6 passes today reverse started acting up had to rev up arround 1500-1600rpm to get it to take reverse then it would back up fine.all forward gears good. The valve body came with new spring for pump, i did leave the center seal out of direct drum and the 2nd ring off center suport. there is not a core plug in the case in the reverse passage. all checkballs removed per instructions and removed the sealing rings off the rear servo accum piston. Any ideas on were i should start looking.Trans still in car. Thanks for reading and any suggestions.