If there was some bowl porting done to the heads I would say the XE274 would be the one I picked and a good 3000 stall converter.
You did say ragged edge though and that would make me want a really good converter like a coan in the 4000 stall area.
Watch these 2 videos same long block in both vehicles First is a 47 dodge 3376 lbs with me in it.
3.25 rear gear 2500 stall 268H cam on a 106LSA long block is standard crank and standard bore 601 heads ported with 1.84-1.50 valves and Z springs in it at this time Stock Delco HEI, RPM intake and 750 edelbrock 1407 carb.
The tires are 28.5" tall TH350 with that 3.25 gear first gear runs to 70 MPH.. so what Reelysalty stated about a gear change is truth. Sorry kind of crappy video all I own is a 3.2 MP sony camera.
Now the same heads and block and transmission into a much heavier vehicle with my 250 lb son in it with me the
weight is 3900 lbs.
But it has 4.56 rear gear and a Coan 4500 stall which at the top end slips less than the 2500 stall in the much lighter vehicle. Quality converter vs old GM bent vane deal.
Intake is now a tunnel-ram and 2 edelbrock 1405 600 cfm carbs Single point distributor.
And the cam was changed to the 280H because I was getting beat on the top end with the smaller 268H.
I broke a couple Z springs and this one has Pac beehive Trick flow brand 313 rate same 110 seat pressure as the Z springs.
I like driving this set up way better. Gears and converter a big yes.
Notice the idle and driving away from idle speed the 4500 stall does not act like a cheap 4500 stall.
Currently I have a tight 1500 stall in the car and RPM intake with a 1407 carb and 3.70 gears.
Not as much punch but pulls my pontoon much better.
I would have kept the tunnel-ram but when i went to the store shopping I kept thinking someone is going to steal those carbs or air filters.
30 years ago I was not worried about people taking stuff.