I think those are really good choices for the retro pack(aside from Shipment, which is way too small). Some of the levels just wouldnt work with the new killstreaks, such as Bog(too open), Shipment(too small) or Showdown(no cover. The chopper gunner bullets will be able to reach you anywhere on the map except for the two middle tunnels. Upstairs wont protect you due to CGs being able to fire close to an opening and still kill you.)
Vacant is a great map. Theres a couple holes in the roof and some windows to shoot people if they get to close to the edges, but overall theres a lot of air cover so killstreaks wont ruin it. Has the long sightlines for snipers that want to shoot down hallways or by the loading dock, and lots of narrow corridors for knife runner/shotgun mayhem.
Crash was one of my favorite maps out of CoD4, along with Ambush, Bog and Crossfire. Its another one where air sightlines arent great but ground level has plenty of combat options.
Overgrown is an ok pick, but I would have preferred Pipeline for a bigger map. However, aside from Wasteland and Derail there arent any really big maps that are well suited to snipers, so I suppose we have to toss those guys a couple levels. Can't wait to knife run up to stone bridge sniper fence or wood bridge busted building and tear through like 4 guys with their backs turned. Good times.
EDIT: I think the best levels out of CoD4 for a retro pack[based on absolutely nothing except opinions on what should be ok, but really dont know because of the new perks and air support] would be Crash, Pipeline, Vacant, Crossfire, Downpour and yet again Chinatown/Carentan.
Please do not give us Shipment, Bog, Ambush, Wet Work, Creek or Countdown.
The others should be ok, and theres plenty of "just ok" maps already, so whatever.
vvv Hahaha...no, Shipment is not even close to the size of Rust. Think more 1/4 to 1/3 of that size and then you'll be on the right track. It would be an absolute shitshow with runners, and a single AC130 shot could hit either everybody in the middle t or on the outside along those lines(if it got aimed right in the middle of the map between the boxes) or an entire half of the map on the outside.