Can it be done if the budget doesnt stretch far enough yet for lower and upper manifolds?

Yes, its a straight bolt up
It will still go alright, go to T Moss Porting and see what he says to do to the HO manifold....impressive

you might need to change your spark plug leads. a couple need 90 deg boots to fit, as the spark plug angle is different, and sometimes a b**ch to get in and out, otherwise, not a problem.
Try and find an Explorer (AU) manifold too if you can, the ho manifolds arent worth playing with.