Back 45 some odd years ago I had a 57 Chevy with a 327 and a Muncie M20. One of my friends gave me (if I remember correctly) a Hays aluminum flywheel. It had an iron insert that could be replaced, and the weight was around 20 pounds (again, I'm trying to think back that far, so it may have been even less!)
Anyway, I ran it for 2 months before I ripped it out in favor of the stock 11" iron flywheel. Every time I took off, I had to get the revs up to 6k just so the car would move! Anything lower than that and I would either have to ride the clutch, or stall the car! It just wasn't worth the effort.
The L88 flywheel weighs around the same as that Hays flywheel I had, so think twice before using it. They (like the Hays) were meant for racing.
Did you have your original flywheel surfaced before you installed the McLeod clutch? I'm not familiar with the "Super Street Pro", but from their web site it's a dual disc clutch, so it may take a few more miles before everything seats. If their tech support says wait until you get to 500 miles, then take their word for it. If you still get chatter after that, check your flywheel and/or call them back.
Ed