Too much pressure??

I'm trying to bring a recently-purchased sleeping 273 back to life after it's been sitting idle for about 15 years. It's a 1965 180 HP with a newly rebuilt Carter 1781 2 bbl carb. After doing all of the other prep (oil, etc), the time came to try to start it. I began by trying a little starting fluid & after a little cranking, it STARTED!....It ran for a couple of seconds until the starting fluid ran out. I then hooked up the fuel line, expecting success. No such luck. I discovered the fuel pump was not delivering any gas, so I replaced it with a new over-the-counter pump for this car (the brand escapes me) & gave it another go. This time it started, but I got the "KILL IT" signal from the guy watching the engine - there was gas coming through the top of the bowl of the carb above the floats (accelerator pump?) and the base. I've tried a few adjustments, including a new needle & seat & gasket but the problem continues whenever I have the fuel line hooked up. Clearly(?) I'm getting too much gas & the new needle & seat aren't doing their job to stop the flow when the floats reach the highest point - about 1/4 inch from the top of the bowl. I tested the fuel pump pressure (while cranking - remember it won't keep running with the fuel line connected). The fuel pump pressure reads 7.5. The specs I see for this engine range from 5-7. Would that extra 1/2 lb of pressure make enough difference to cause my problem?...or what am I doing wrong? Would a fuel pressure regulator/gauge be the most reasonable cure? I feel like I'm really close, but......