You guys keep this up and I'm going to retire!
Peteks installation is exactly the way we install it. If you bend the straps right, the heater will sit tight up against the firewal, which leaves more than ample room between it and the dash. The radio if used will still have plenty of clearance.
If you use two 90' fittings off the heater you can bring the hoses up through the firewall - tunnel. This makes for a super clean installaton.
Nice job fella!
(edit) You'll find that there is not a whole lot of room for your bolts to through the mounting holes of the heater, and then try to put a wrench or socket on the head. Solution... simply take a hair dryer, put it on HI and heat the area where the head sits. I then use about a 1/2 deepwell socket, placing it as if I was putting it on the head of the bolt, and push in toward the heater core.
The plastic will flex very easily when it's warm, leaving plenty of room for your final assembly. Just another little tid bit for easy installation.
DV -- 300 Cobras is NOT enough! Are you registered?