now granted this is a different animal but our 528 race hemi in a landy dart clone is in the same range as yours... should be traping around 6800 and is @ 7200...
we tried to have them tighten up the converter more but with no luck... so were going to try 4.10's (from .56's)...
P.S. strange is the only make of 4.30's for a D60...