Yep the a12a rods usually are the stroker option, Not sure anything out there aftermarket but usually stock Nissan is stronger. There are some peeps in the past that turboed the A15 with non forgies If I remember right he had a 1000 wagon and was pushing over 20psi with meth/water in a very simple drawthrough setup. To go really cheap you might be able to get some new A15 factory pistons from yahoo auctions and an A14 crank locally for 80-100 aud.

Lags was right though, if all your components are good as they are better just refresh it and start with that to get the ball rolling and gain confidence for perhaps a better prepped bigger A12 stroker bottom end in the future and a cam to suit. Sykines suggestion of e85 I would never look past that.
The only bit I would change is to go oval port h89 head, stock proven to be great for boost and then you wont waste money going from round to oval port.