Welcome to the forum.
The torsion bar suspension is actually superior in some respects to the later coil spring replacement design. The reason very few owners stay with the original suspension on modified trucks is due to cost, and limited support in the aftermarket.
Almost everything suspension interchanges from 63-72. 60-62 is all by itself. Replacement parts like ball joints and steering parts can cost up to ten times as much compared to 63 and up pieces.
The torsion bars can interfere with long tube headers, and the convertible/perimeter frame under the 60-62 is more troublesome for routing exhaust, etc compared to the simple ladder frame of the 63-66. There are a few new lowering spindle parts and brake kits for the 60-62 chassis, but almost no other aftermarket support. Most people update to the later chassis parts simply because it’s easy and cheap. I switched to a 75 front suspension many years ago mainly because the import ball bearings for the front wheels kept failing at great expense. Had I known I could have used 62 hubs which are stock with tapered roller bearings, I may have considered leaving the T-Bars in place.
If you want to convert this thread may help:
http://67-72chevytrucks.com/vboard/s...d.php?t=366828
And this thread deals with engine and transmission mounts:
http://67-72chevytrucks.com/vboard/s...d.php?t=369663
You can drop the front end by releasing tension on the torsion bars, but there’s a limit. The farther the drop, the more the adjusting arms point toward the ground. Too much drop and they will become a road hazard.