You have two options..
1. spend the money on cams and a remap and then some decent shocks and springs. Even then, you will still be underpowered compared to a standard 16v ABF
2. Sell the 8v buy a decent 16v ABF and do alll the above, should see some gains and it will more then you would get from the 8v also costing around the same.
In thoery, the money spent on the 16v compared to the 8v would more or less the same if you were to do simular mods. The gains however would be much more in favour of the 16v
Khare is a good example as he cammed his 8v yet he still decided to go for the ABF
