Barry, you might consider staining your alum valve covers instead of painting them. I think it gives a more natural look than the solid colour painted look.
I take the cap from a spray can and put paint thinner in it, about 1/4 full. Then I spray some alumi-blast into the thinners, just a shot or two. Voila...
your own alumi-blast stain. Next I brush the mixture onto one valve cover with a regular paint brush. Then I immediately start brushing on straight thinners to clean the stain off. I do this several times (just thinners). I read about this technique several years ago in a NCRS Driveline article and have used it several times with great success.
You could try it and if not happy, then go wild with the spray bomb.
When you do your intake make sure it is really really clean first. I find that just a dusting of the alumi-blast gives a nice look.
If you manage to do your intake and valve covers without a problem, then your exhaust manifolds will be a snap.