[84LX89GT]

original 302 windsor heads have very small ports and as such give good low-mid rpm performance but kind of wheeze on upper rpms. Usually a good set of windsor heads is more than enough and having some worked windsor heads will give you a great torque band assuming you don't have alot extreme stuff and they're good for a daily driven vehicle.

Cleveland heads come in two variations. There are 2 barrel 351C and 351M and 400M heads, and 4 barrel Boss 302, 351 Cleveland 4V heads. The 4 barrel heads have GIGANTIC ports and breathe best above 4,000 rpm and are not very good on 289/302 mustangs in terms of street use. the 2 Barrel heads make for good street heads, but to be used on a windsor block you'll have to have custom headers, use a 302 cleveland intake manifold. This is only on the 4BBL heads, there was never a 2 barrel "small port" 302 cleveland so there aren't any intake manifolds available.
You'd also have to have the Cleveland heads adapted for use on the windsor block. so the streetable 2 barrel open chamber heads are basically out of the question.) The Clevelands had coolant run differently through the heads so some areas have to be tapped and others plugged. There's actually quite a bit of information in the internet about swapping over.

If i were you i'd get a good set of windsor heads, swapping over to cleveland heads, although unique, is very cost intensive.
Not only that but you can make alot more usable power with a set of windsor heads on your combination. Even a set of stock heads that are Ported/large valves will give you quite a bit more power.
Good luck.