First off, you'll need a Holley throttle lever extension, like this one here.
http://www.shop.speedunlimited.com/...fp/SFV/32401/vpid/4082455/vpcsid/0/rid/126429
The bracket that holds the kickdown linkage and accelerator cable is taller on 4V manifolds. If memory serves, it also moves the clamping point slightly further ahead. There are several suppliers that sell reproductions of the original pieces, Lokar sells aftermarket replacements, or you can make the original work if you have welding tools and the skills to use them.
http://www.yearone.com/serverfiles/fbshopmain2.asp?hid=114AG31
My experience extends only to 67 and later A bodies, it's going to require someone with pre 67 experience for specifics on the earlier throttle linkage.
I don't know what the junkyard situation is like where you are, around here you pretty much only find factory 4 barrel maniolds on later model vans and pickups, and the odd Diplomat style cars, and I am not sure if the brackets from these can be adapted.
As far as jetting is concerned, buying a Holley strip tuning kit with an assortment of jets would be a good idea.
http://www.shop.speedunlimited.com/Shop/Control/Product/fp/vpid/4082465/vpcsid/0/SFV/32401
The quick change kit and an assortment of secondary springs is also a good idea.
http://www.shop.speedunlimited.com/Shop/Control/fp/scat/124027/SFV/32401
Here is a PDF file on Holley 600 cfm carbs, list #1850, the common as dirt 600 cfm carb.
http://www.holley.com/data/Products/Technical/199R7948-5.pdf
God I love Google....
This should give you an idea as to how these were jetted as produced, and give you a starting point for jetting, etc.
There is a number stamped on the choke tower (facing the front of the car as mounted) and this number will tell you what carb you actually have. You can search for the specs and intended application to find out what it came from, etc. Here is one of many.
http://www.mortec.com/carbs.htm
The search I did....
http://www.google.com/search?hl=en&q=holley+carb+list+numbers&aq=f&oq=
Whether it's a vacuum secondary or double pumper carb, it can be made to work. Double pumper, mechanical secondary carbs are just harder to work
with especially on a mild engine with an automatic.
Start with this, I'll lend any help I can.
Alan
Alan