Here's my 340 build in the 70's and the first engine I ever built.
340 stock bore stock stroke
stock 10.5-1 heads 2.02 valve and slightly cleaned up with sanding rolls and a drill.
590 lift solid cam
273 adjustable rockers
Offenhauser portasonic intake.
850 holley
727 trans 3800 stall turbo action converter.
4:56 gear 3150 pound car
headers
Drove it to the track on formula one super stock tires unhooked the headers and ran an 11.82 on sunoco 94

2nd engine built was a 340 for a Friend and I charged him 5 dollars to build. (I bought 5 dollars of hot balls and jawbreakers to share)
340 stock bore, stock crank, rods, and pistons.
new out of the box rings and bearings.
484 purple shaft hydraulic cam.
750 holley
2.02 valved heads
headers
727 trans and my 3800 turbo action, 4.56 gear, 3100 pounds
12.21 quarter-mile first time he ever went to a drag-strip.
I would highly recommend a set of edelbrock heads to assist with running pump gas and an LD340 intake.
Here's my old car and me many years ago. (I'm 57 now)