Been seeching for some info about this and could find mutch for my specific purpose but I just bought a bridgeport 74-78 13b 4 port motor big mazda leters in a box full swap (oil pan front cover notched mount w/an fb tranny for my fb and want to know what size jets I would use in my stock 12a niki for the best results trying to verify its a healthy motor and being able to drive it around for a bit because not entirely sure it's good all surfaces look good and it sounds like it has compression and I'm going to compression test it tomorrow morning after i drop it in. I'm a little tight on funds and I don't want to drop 1500+ on a carb and manifold setup if the motor needs rebuilt (rather pay for that first). Also bonus question will a holly bolt up to an old 70s 13b intake manifold with mild modified/porting

 

The Nikki will work fine like it is. To make the most power, you would need to do some work on it though.
The old 13b intake will need to be modified either way. For the nikki, you will need to drill holes and move the studs inward to match the Nikki bolt pattern.
You can make an adapter(not that hard) and make the holly fit that intake also.
hope this helps! good luck!

 

I made an adaptor to fit my FB nikki manifold to the 13B. 3/16" plate IIRC.

I ran an S4 turbo on that engine through the Nikki; so I'm sure the Nikki can keep up with an N/A 13B.

If you are in the market for an early 13B holley manifold; I have a J-tech intake for an early 13B 4 port engine I'm motivated to get rid of.

 

It was already premodified from the previous owner so I just tossed my old 12a niki on it and it fired up idle still Needs upped alot but it drove great also do you know if idle up is in or out on the nikis the bridgport won't even idle at the 800 rmp my cars set to so I don't have a starting point to just figure it out myself