the poly/hemi flywheel is only a 3 tooth count off being the same (as a modern flywheel)--you can also elongate the top starter bolt hole 1/8 inch to rotate the starter out----and there is enough room on the flywheel to drill and tap holes for the modern 11 inch clutch.....and i have run the 3500/3550 5 speeds because they are easier to find that a small block bellhousing with a 883 and assorted clutch linkage/shifter......