Ultimatley I think the cheapest way for big performance would be to put 20v 1.8 turbo in it and just chip it I reckon.
But for close to 200+ bhp from the ABF, the exhaust/manifold, induction filter, mild cam, chip, polished/ported head in my opinion would do it. + a lightened flywheel for better acceleration.
Done all that on a couple of Vauxhall 16V's with great results.