I'm excited for your project! Hope I'm not contributing more than you want to know/hear.
The Hemi book is your best source or comparative info. It's outta print but can probably be found used.
Stress contacting http://www.hothemiheads.com/
----In my opinion, everything you need to consider has nothing to do with valve/lifter angles. It is what it is on your engine and any mod for waterpump or engine mounting has nothing to do with that subject. BTW, Speedway Motors has an engine mount that will work for your custom installation.
----Re-reading your original post,,....I believe the '54-'55 heads are the same as your '51-'53 heads. Hemi heads all flow exceptionally well. Yes, later heads, like '56-57 flow better but not to the point that you would notice the diff. unless you have a really big cam and are racing your car to a high RPM. Save your money. Buy some headers. Maybe spend your time matching ports.
Your 2x4 Weiand manifold should be aluminum and worth something. The factory 4 bbl is likely iron. Save the weight. Learn how to rebuild the carburetors on YouTube.
Also one of our forum members "Wayfarer" is very knowledgeable and may be able to provide some parts and references.
Good luck,...keep posting,.... send me a "private message" if you wish.
Where you at???????