Most people who use a vnt say it's the best turbo for the five, same delivery as a t28 just a lot earlier in the rev range. With EFI if you want a punchy road/track car then the vnt gets my vote.
Was it Phil with the ace minty red five who used one and his engine did 260hp with a similar spec to yours. From memory he had an awful lot of head work done also.
With a 60 trim T28 with efi and good mapping you might get Full boost at 4k rpm or so. With a vnt i think it's similar or even earlyer than a t2