[66coupe289]

From those choices
1 Edelbrock Performer RPM, skip the air gap and avoid the Performer.
2 Weiand Stealth

Yep, and in that order. (some may consider them 1a / 1b choices)

 

[66coupe289]

You mentioned a lack of low end. This is a torque issue with the 289, not an intake issue; going with a bigger manifold that makes more peak horsepower will also hurt your off-idle and low RPM performance. The Performer RPM and Weiand Stealth are both excellent manifolds, otherwise, and flat out superior at higher RPMs. If you're running bigger numeric gears to overcome the low RPM torque deficiency, I'd say they're a good bet for sure, but you may find that they slow you down more than they help with a mostly stock 289, especially if it's a 289 2V backed with an automatic and stock torque converter.

Agreed. The best way to improve torque on a small block is with rear end gears.

I noticed no loss of torque/power going from a Performer to Performer RPM, but my engine had a few other upgrades over stock at the time.