If you mate has a 2.8 then get that lump from him for the pistons. Take your lump out and rebuild your bottom end and bore out to 93mm (i think) and use the v6 pistons. Cheap, only cost about 60 quid to be bored plus shells and rings.

Spend the rest of your money on head work. Something has to be done with the rods? I sure someone can tell you what.