Here's my story. I've posted it here before, but it goes to your issue.
I had a SV for many years. In high school I loved pushing it hard. Then it sat for about 4 years while I was away at school. Upon graduation, I bought a Porsche 911 and the Sunbeam sat some more. Then I got the Alpine running. It seemed all good and everything, but little umph. At the time, I assumed it was because I was used to the 911. I was debating what to do.
As a kid, I always dreamed of hopping it up. Making it a bat out of hell that would scream down the street. At the time, I didn't have the money and I didn't think anything was available. I had heard of side draft Webers as the ultimate in 60's performance. But, that was about it. The V6 route really didn't interest me as I saw my Alpine as a British four banger, and wanted to keep it that way. I did think about the Capri/Pinto overhead cam 2 liter. But, not being a British engine didn't sit right for my Alpine. Also, it would require the help of others for welding and custom work and I wanted to be able to bolt and play by myself.
Then I stumbled onto a NOS Holbay head. The gears started turning. Next thing I knew, I had the NOS Holbay head, a H120 Holbay cam, the dual 40 DCOE 151 Webers, and I was off to the machine shop. The car turned out fantastic - with lots of other fun stuff, like custom pistons, lightened flywheel, head ported further, three way grind, custom exhaust pipes to match the larger Holbay exhaust ports, OD tranny, etc etc, oh, and custom rebuilt distributor to eliminate the vacuum advance and match the performance of the engine.
Ahh, but here comes the surprise. In pulling apart the distributor to recurve it, what should we discover? The weights had rusted/frozen in place during its slumber. So, when I was driving it, and it seemed so slow, it was because I had NO ADVANCE! Thus, ironically, the thing that started me down the Holbay path was all wrong. So, I agree with the other person that the stock Alpine can be great all by itself, when running properly. You don't need to invest tons of money to have a great and rewarding car. That said, I love my car now and it does really scream down the street like a bat out of hell. It LOVES high rpm and breaths soooo nicely up there. It's up to you how much that is worth.
That all said, even with the Holbay set up, the V6 set up, the 2 liter or 2.3 liter set up, or even the injection set up, you're still going to have a hard time beating the soccer mom off the line with her Minivan loaded with kids, with the AC cooling and the radio soothing. "Mom, why is that guy next to us in the funny little car, making all that noise as we pass him, have such a sad look on his face?"
