Yes, solid lifters. We put pushrods in it too many times... If revved to 5,600 in the lower gears, it was fine. Over 6,000, and it would bend a bunch of the pushrods. In 4th gear, it would go right near 7,000 without a wimper. I suspect it was catching revs too quickly for the stock valve train in the lower gears. Definitely a 3.50 gear, as well. 3310 Holley, if memory serves me.
I have a '69 Torino 428CJ in here right now. The car is white with red "c" stripes, and red interior. It's quite nice! Girl's car, though (auto trans).
I have seen at least three or four '70 Mach 1s with 429s in them. They may have been transplants, I guess. MUCH stronger than the 428 cars. I drove a '71 "flat back" Mach 1 with 429 CJ. It was a GOOD running car, despite the lower compression. My favorite Mustang was always the flat back. My brother (a DIE HARD Mustang guy) hates them. He says they're just to damn big. That's what I LIKE about them... They're the most aero Mustang produced, too.
When I was first getting into my own cars, I was a "Ford guy". Then, I bought The Judge. You're right! SWEET RIDE!!! Never looked back. GTO was by far, the best balanced muscle car. If you could beat it in a straight line, it would stomp you in the twisties. If you could out-handle it, you were toast in a drag race. In SoCal, there's lots of good places to road race and drag race. We had "courses" marked all over the San Bernardino area. Hwy 18 to Big Bear is an AWESOME "GTO road", at least UP HILL. Down hill? Not suicidal...
Jim