The 94 that I had came with the GTP40 heads on it. Only thing I can tell you is you will have to watch your header clearances with those heads. The sparkplugs are rotated a bit from other regular Windsor heads. The no 6 plug if I remember right you will need to put in before you put the headers on the driver's side as you can't get to it with the exaust bolted up unless you have headers for those heads. Also make sure you do have the correct sparkplugs as they don't use the same plugs as a regular Windsor either, AWFS 32-C if I remember right are the right ones for them as they have a longer thread. Also regular 135 deg Ford sparkplug wires don't work on them either. They will shove the boots right against the headers melting them or burning holes in em in no time.. I used 90 deg Chev plug wires and they cleared just fine. You will pick up about 1 point in compression due to the smaller combustion chamber, and if you plan on running a cam with a lift over .500 you will need to change out the valve springs because at about .490 or so the stock springs will start to bottom out. Im not trying to deter you from running these heads as they are a great bolt-ons and you can pick up good power just by putting em on, just letting you know ahead of time what I've found out from my experience with em and maybe this will make it easier for you to be prepared for em when you get ready for em. Cheers!!
