What about the backwards head gasket issue? I know it's a pain in the butt, but you have to get that right.
Surge can is completely unnecessary unless you have air in the system or don't have a high point for filling.
The rear air bleed is a great idea. I would not install a valve...you want that bleed path present all the time in the event of thermonucleatic boiling in the heads that cause air pockets to form over time. You know those tiny bubbles that seemingly form out of nowhere on the bottom of your sauce pan when making pasta? That happens in your heads too. Those tiny air bubbles will collect back there and before you know it, you have a big air pocket. Look at some factory high performance engine designs and you'll find these bleed paths are either there from the factory, or added afterwards by those that push their engines and have discovered the problem.
Timing is unlikely to do what you're describing. If it was that far off, your exhaust would be glowing red or it would be running so bad you wouldn't have had it running for that long before you shut it off.
A mechanical fan and shroud will provide more flow than your planned pushers. If you want powerful pushers, look at SPALs offerings. Push fans are not nearly as effective as pull fans. You will burn twice the amps making a push fan work. Do this only if you have to; pull fans are much better if you have the room for it. I didn't have room; believe me I tried; and am running a pair of powerful SPAL pusher fans. They draw over 80amps at first power on, and over 40 amps sustained on high. I run a 200A alternator mostly because of the fans.
http://www.racesystems.com/cobra/ima...nSpal1750s.jpg
My radiator is a huge, heavy, ridiculous brass monster made by some supplier for West Coast Cobra in Canada. If the car is moving at all, the fans are off. This includes road race duty in hot weather. They don't come on until I pit. I hate the weight and bulk and over-all appearance of the radiator, but boy does it work.
http://www.racesystems.com/cobra/images/radiator2.jpg
If I did it all over again, I'd let Matt design the whole thing...radiator, fan, and Shroud assembly...with my Meziere water pump built into the radiator tank. That would probably take 30lbs off the nose of the car.
https://the-fan-man.com He's also a good source for the SPAL fans if you're looking for them.