I'm in the process of doing a 302 / 5.0 Build & I just thought I'd give others a Heads Up on doing this & the problems associated with it. My car is a 94 GT.
The Heads are GT40 (3-Bar) Heads off a 96 Explorer. I'm using a Ford Racing E303 Cam so I have to upgrade my Valve Springs & Push Rods. I'm also using 1.6 Roller Rockers. I'm using Dual Coil Valve Springs with Damper & because of the Cam I also HAVE TO USE VITON SEALS & can not use the stock type as they wont fit the springs or hold the pressure. Doesn't sound like a big deal...But it ads $200 in machine work to the heads to re-size the Valve Guide Bosses & Grind that Step around the bosses down Flat so everything will work.
So you're looking at: $200 = Roller Rockers, $60= Hardened Push Rods, $100 = Valve Springs, $10= Valve Seals, $30 = Rocker Channel Guides, $65 = New Retainers,
$10 = Hardened Valve Stem Locks, +++ $200 in Machine work on top of whatever you pay for the Heads.
Also I think I may have run into another problem with the heads...Not sure yet as this is something I was just told today. I was told the GT40 Heads have no Air Injection Ports for the Smog Pump. I live where I have to pass emissions so ....well...not sure what to do yet. I'd like to delete it but not sure i could get through emissions if I do.
My advice after learning the hard way...DON"T DO IT !!!!!
Buy yourself some aluminum heads as you'll end up paying close to the same price.
The GT40 Intake isn't a Big Deal. On 94-95 Mustangs you have to buy a Throttle Body Elbow & mine I got for $65 New on Ebay.
Hope this helps those decide which way to go who are thinking about doing a build.
Sure wish I'd of Built a 351 instead now.