Swap A833 for Auto - 71 Duster 340

the compression test will tell a lot.
According to Wiki, Iowa has elevations ranging from 480 to 1670.. On an 8/1 340 that change is worth 6psi.
If you are starting with an 8/1 engine, with a factory 340 cam, your pressure at 1000ft is predicted to be 120psi or less, making it feel pretty soft, I mean really soft down low, especially with a 2000 or less stall TC. There is no cure for this, except more pressure.
You can bandaid it with more stall or a mote rear gear, or a clutch, but those only help you get moving. The low pressure is just a sad thing thru out the rpm range.
There are a couple of ways to get more pressure, but the best is to get the pistons closer to zero-deck.

But hang on; this is 2020 and that engine is nearly 50 years old. There is no telling what pistons are already in there as they are not likely to be the original... so
the compression test will tell a lot.