Pushrods measure 7.530 . you are right they are not the right length, but are correct for a stock 340. There is probably enough wear on the old factory rocker combined with a smaller base circle on the cam to get to that lash. Yes it has been this way from the first time I started the engine.
Sounds like it's not a STOCK 340 so that number goes out the window ... as you can see.
Get a checking pushrod , figure out the length needed , do a few on both banks , and by an ADJUSTABLE length pushrod from Smith Brothers and call it done .
Adjust each pushrod to get the amount of preload you want on every lifter.
