Yeah, I think you did meet my dad. My brother used to live in Saint Robert and they told me they met a guy who had a '67 Red/black Comet down there (and now that i think of it, they mentioned your 4.11 gears...seriously...). Small world, man. I tell my dad I found you on here; he will be pretty excited about it. Would be cool for you all get togethe and get some pics of both your cars.
MT Et Streets are excellent tires, My uncle has a vortech-charged '02 Z28 pushing 500+ to the wheels and he uses them with a trans
brake and a Turbo 400, he has no problems with traction (he is dipping into the high 10s). I highly doudt it's the tires. Do you have Traction bars on your rear leaf springs? May be something to look into. The SFC are a must...
If you can get up to STL and check Mustang Muscle out they are very good. The owner is my cousins step-dad so basically family and they do good work.
Before changing out rear gears, get the chassis/suspension in line. My dad runs the MT ET streets as well with 3.70s, subframes, no traction bars (he is pushing 420+ to the wheels) and he has no issues with traction either. I really think if you dial in the suspension/chassis yours 60fts will drop significantly.
Very cool to see you on here. I'll let my pops know I ran into you on here. PM me if you want.