I am going to be going big block in my 65. I am trying to look ahead and find out if I am going to run into any unforeseen problems or issues to deal with.
I have an 11" booster now and think there might be a clearance issue with the valve cover, hopefully someone can give me some direction on this.
Headers I realize might be a problem but hopefully can draw on someones experience here to buy the right ones first time.
I have an electric fan setup now that I built and know it won't work but can work that out. I might even need a bigger rad, not sure but am aware of it so it won't surprise me if I do.
I have to research the engine stands and mounts yet to make sure I have the right parts.
Hood clearance I think should be ok if I use the right intake I assume??
I am pretty sure I will need a different z bar for the clutch.

Any other things I should be considering guys?

You could buy a '65 with a BBC so you should have no problems.

Mine fits ok, used Hooker 2 inch headers. I dimpled the tube near the steering shaft.

I have the 7 inch booster which fits fine and you can run tall valve covers with it.

I had some trouble with the oil pan hitting the crossmember. It was close when I got the car and when I rebuilt everything and set the motor back in, I couldn't get the bolts thru the motor mount holes. I elongated the holes and wasn't satisfied with that, so I removed the frame mounts from the frame and put the mounts and frame mounts on the motor, cut some 3/4 inch steel for shims between the frame and saddles. Then set the motor back down and welded the shims and horns back on the frame. Still had enough room for a big air cleaner.

Possibly I don't have the correct oil pan, but if it was wrong, I don't think it would be anywhere close. My motor is from a 66 Chevelle, so it should have a Chevelle pan, anyway.

Hood clearance