Most of the guys in my circle running a 440 based stroker are using a 9.5" convertor. We would have the same problem if we went to an 8" like your running..I do not think there is enough holding power in an 8" for a stroker.
I have ran 8 inch converters in everything from 11 second footbrake cars to 7 second dragsters and have one in my Dart now that 60 fts 1.19....
He is quite a ways from blowing through the tightest 8 inch you can make. IF its done right.....
I asked a reputable converter guy about where the cutoff was for an 8 inch one time and he said probably around 3000lbs and 900 hp.....
