The 5.565 rods are fine to use in a 307 with the 3.250 inch stroke.
This gives it a rod ratio of 1.7:1 which is good for a street engine.
If you went with Vortec heads, had the block decked .012 and used a GM 4 inch bore .028 compressed thickness head gasket you would land right at 9.5:1 compression ratio which is ideal for the street on pump gas.
It would also put the quench distance at around .041 which is also ideal.
Run a dual plane Vortec intake and a Quadrajet on top, with small tube headers and a summit hydraulic flat tappet cam with .214 Duration @.050
and .440 lift, tune it up with the best pieces you can afford.
What you'll have is a strong running street 307 with outstanding throttle response and good fuel economy to boot.