Yes I know you have a 4speed for it,
and I know the little 273 can be fun with a 4-speed. But. if you go the performance route that most guys go, yur probably better off with a higher stall/auto/and big gears.
As for me, if I had to run a 273/Mopar4-speed, I would order up a Commando gearset, a GVod, and 3.91s, and start splitting gears;
Road gears with 3.91s would be;
12.08/9.42--7.51/5.85--5.47/4.27--3.05 Gearvendor splits in red.
Not all gears can be used sequentially. Normally, I shift; 12.08-7.51-5.47-4.27-3.05 ;splits are progressive, at ........ .62---.73--.78--.71od, But
When I'm showing off, I shift;
12.08-9.42-7.51-5.47-3.05 splits of
...... 78---.80--.78--.56od
The 5.47 gear will get you 5000=73mph; that's One tug on the stick, and Two electric shifts.
The 3.05gear gets you 73 mph at 2770rpm; 65 at 2470
Sounds like fun but
I'd rather run a 4-speed Torqeflite LU