well you can there is a japaneeeeeeese guy making the the twin turbo ducting and selling the turbos on ebay for ???? money i dont remember but i have seen them on there numerous times
You don't need twin-turbo to be fast. Just look at the trends for many Mk4 and GT-R, single turbo. If you don't mind some lag, then save yourself money and problems and stay single turbo.
Put the money you save into head and intake work, that will make the most of it.
I have a link on my comp. at home(im on the work comp. now)Of a tt setup on an L28.Im not sure if they bored it out any but i will check when i get home tonight.And post up the link they have a few more bad ass Z's on the page.
jeff P has a bored out 280ZX at 3.1 and hes pushing a little over 415 hp @ 473 foot lbs of torque... and his clutch barly held up.. i think 620HP is a little too much.. but heres his web page.. probably the best built 280ZX out there...
Yes it is possible with an L28 but you will be shelling out major $$$$ to make it that powerful. If you have the $$$$, I'd suggest an RB26DETT, or a V8 (SBC) swap.
And for information regarding building an L28ET, RB26 OR SBC with that much power: HybridZ