Turbo Coupe, Merkur XR4ti and Mustang SVO heads are the same. N/A non-turbo heads are completely different. Turbo heads have somewhat D-shaped combustion chambers and, I believe the chamber volume is different. They also have D-shaped ports and exhaust valves made from Iconel to withstand the heat and pressures. N/A non-turbo heads have heart shaped chambers and round ports. The flow characteristics between the two is night and day! You can get a N/A head to flow like a stock turbo head but it requires a ton of machine work (read expensive)!
If your shooting for 300 hp, forget the N/A head! $700 seems alittle steep for a turbo motor although if it's low mileage and tight, it might be worth it. You can get a rering kit for $140, 4 new slugs for $250 and machine work for another couple of hundred. If you can find a junked turbo motor for cheap, you could almost rebuild it for $700.
You didn't mention if the turbo motor comes with a head or not. Forget the N/A head for $450! If you can find an uncracked turbo head for $100-$150, send it to Boport and for $300 he'll give you an awesomely ported and reworked head that'll flow circles around a stock turbo head and would put a reworked N/A head to shame!
__________________ '89 LX ragtop with turbo'd TC motor - Thunderstang!
'86 Turbo Coupe (daily driver)
'88 Turbo Coupe (parts car) | 
2.3L Heads-Can you help?(non turbo,svo, turbo coupe, merkur, ect...) 
