well id like to do 65 with ease. right now its turnin and burnin to do 60. Ive been running a ford 2 ton with a two speed rear and 3 spd brown lipe. Im getting ready to take it down and repaint and repower with a 255 merc. so I am trying to at least get the same top end out of this chevy. when not working the trucks I really enjoy just driving them. Its nothing for me to drive 60 miles one way. So i like having enough gear to work them and when Im not loaded I want to do highway speeds. my ford can do 60 pretty easy but its got a 5.83 rear and .74 OD. Once it hits 2400 rpm it quits pullin. Its got plenty of throttle left just not enough torque. I figure a 261 should make a bit more power than even the 255 merc I am plnning on building