They eventually sieze if run at 85 mph five days a week. Seems a pity to wreck hard to get bits like 301 barrels and pistons going to work when the Bonneville, which is actually in rougher condition, will do it easily and can be kept up to with bits off e-bay. If the M-62 runs at 55 MPH OTOH, it'll be a flip up as to which works best.
Andy