I have nearly the exact same setup in my 78 1/2 ton truck, except that I am using a XE268 cam and a 600 edelbrock carb. I also am using the vortec heads and they are great. I just bought a K-kit and it has everything you need...cam, lifters, springs, locks, retainers, timing chain, valve seals (they wont work on the vortec heads) and lube. Everything fit great and the price was good (purchased thru summit racing). Heres a thought to consider though...you already have a standard pattern rpm intake...you will never see the full potential of the vortec heads if you use a standard intake because of the rather severe port mismatch. So, if you purchase the vortec heads ($400-425), you will need a matching performer rpm intake ($175), a set of centerbolt valve covers (I think i gave about $50 for plain black ones with new bolts, breather, and oil fill cap), a set of rail tip rockers ($50 for stock replacements, or $150 for comp cams magnum roller tip guided rockers), and of course the matching valve springs. Grand total is about $700 not including gaskets and bolts or the added expense of the valvetrain parts. The intake gasket alone was like $26...I purchased the heads, edelbrock performer rpm intake, valve covers, all the bolts and gaskets (except for the head gaskets), and the valve cover breather and oil fill cap from pace chevrolet...they are very good to deal with and they know their stuff. You can go this route, or for an extra $100 (approx) you can get the tfs heads that already have better valve springs (good to about .560 lift), screw in studs and guideplates, and will accept the intake you already have. Actually, considering you wont need to purchase new springs, locks, and retainers, the end price will be about the same, and you will have a more durable heads with way more power potential....plus the added "oooh, aaaah" factor of aluminum heads. Dont get me wrong, I love the vortec heads and they run great...I went this route because I also needed a new intake and already had the correct rocker arms, but I think you would be better off with the tfs heads. Just my opinion.
And by the way, I built my engine almost identical to the one in chevy hi-performance except mine has a bit more compression and a smaller carb.
375hp 78 Chevy truck
77 Chevy Nova
95 Chevy Lumina 3.4L
and building a 78 Nova