Stock 340 magnum power/performance upgrades advice

[RobVoyles]

Hi, new to the forum, thanks for having me. Just wanted to reach out to you guys and get some advice on the best bang for your buck on increasing performance a bit.
My engine is the stock 340 that came in it completely rebuilt with 11,000 miles on it. The only thing not original to my understanding is the compression ratio which i am told is now 10:5:1 with "j" heads.Don't know if that head ref is stock or makes any difference just mentioned it for a little more info. The trans is the stock 3 speed auto and the rear end i believe is the stock 3.23 ratio it runs about 3000 to 3200 rpm at about 65 mph and has an Edelbrock 4 bbl carb. Any advice would be greatly appreciated and thank you in advance.

[Nacho-RT74]

10.5 CR? High compression pistons ? are you sure about it ? If you do... you can get a huge variety of cams based on that CR to increase power... then header, intake. If the MP chrome ECU box still works like a champ, you don't need anything else to increase power on ignition, EXCEPT if you want spend big dollars on the full EFI system. But on the basic ign system, I don't think an MSD ignition system ( which many ppl could say ) will be a huge gain

And welcome!

[70 sublime]

Go from a 323 to a 355 rear gear would give it a little more zip ?

[Challenger340]

Very surprising to hear that you are not already quite satisfied with the power given the alleged engine details ?
Because IMO...
Even a stock 10.5:1 340 with J Heads and anything even remotely close to the stock 340 "P" camshaft were fairly decent performers when setup correctly ?

"stock 340 that came in it completely rebuilt with 11,000 miles on it. The only thing not original to my understanding is the compression ratio which i am told is now 10:5:1 with "j" heads."

Do you have any Invoices ? .... Documentation ? .... or anything else that verifies "340" and exactly what part numbers are present and were used in the Engine rebuild ?
Because... and just say'in here...
without even that most basic starting point of knowns to work from ?  It's almost impossible to suggest potentially valid upgrades ?
What year of 340 is this ?

Have you even checked thus far the side of the Block casting to verify it's a 340 and not a 318 ? Numbers Matching VIN on the Engine Block for example as well ?

Hard to tell from the Pic ?

But does yours have the '71, 72 and 1973 B Body 340 Drivers side Exhaust Manifold seen here:
Casting Number3418621