Welcome to the forum.
I looked into VBP composite springs again recently, I had their catalog and considered that route back in the early 90's. I was mostly curious whether they were still being made or if VBP was still around.
I have no firsthand experience with their product.
I have seen very few folks here running a composite spring.
CarlC ran them on his 68 Camaro but they were Flex-a-form and he had custom spherical bushings in the front eye. I do believe that he has gone back to a metal spring and that may coincide with the additional power from a Magnuson supercharger.
flex-a-form link
Deaver spherical bushing link
From what I have read here there is somewhat of a hp threshhold indicated at around 500hp. Some say that a leafspring is being asked a bit much to work with that load. You may want to look into alternative suspension setups for the goals you mentioned. I am sure others will be along to mention the vast number of options available for a build like that, and I can think of at least one vendor with ongoing experience shipping parts across the big pond to your neighbors.