The Holley intake will probably only fit the low port heads. I had one on an odd fire V6 years ago in the 70's and it was the best available at that time. The other manifold I ran was the Dual Port Offenhauser. It really choked the engine. I dug through my archives and found some tests run by Kenne Bell in the mid 80's. The engine was an even fire with 10.2 to 1 ratio and a KB Mk 2 cam. The Performer manifold dyno'd at 168 RW HP. The Kenne Bell # 1 saw 207 RW HP. Of course, Kenne Bell was selling manifolds and always claimed they had the best parts no matter what it was. In a light car like yours, a Kenne Bell or Weiand single plain will work fine. In a heavier car, the Performer is probably a better choice for Street/Strip use. I have 2 KB's that are ported to match my ported heads, and they work well with a 600 CFM Edelbrock carb on my stroked 4.1. The 3.8's I have run worked best with a 500 CFM Edelbrock. The difference was noticeable with the smaller carb on a 3.8. I have used Holleys also and they worked well with vacuum secondarys. I would say stick with the Performer if you shift at 5,000. If your cam will pull higher, and your heads are ported, the single plane will probably give you more power. If you plan to use nitrous, you would need the open plenum design. A TR7, or any Triumph, is a perfect swap for a V6. I have my stroked 4.1 in a Toyota pickup with way too much invested in the drivetrain. I often thought about building a TR6 with a V6 Buick.