My father in law's 68 chevelle w 307cid modified with aftermarket heads and cam runs extremely well with my carter 625 cfm i have a almost new edelbrock 750 i would give him but it needs to be tuned obviosly. If i used the same metering rods and springs and jets as the 625 do you guys think ill be okay . Just curiuos i appreciate your thoughts.:hail:

No, the 750 flows more air you need to adjust for both the air and fuel since there will be more air flowing with the 750 you would be very lean with 625 rods and jets. A calibration kit for the 750 would be the ticket.

True.

The jetting/ rods out of a 625 will be too lean/small in a 750.
As others have said, above.
The Chevelle should run real good with stock out of the box
jetting that comes in a edelbrock 750.
Try it as is.
If the car has a big cam, change the power spring.
(lower tension.)
It may want a little leaner part throttle jetting.
(primary jet and rod change) but try it with the stock 750 stuff first.

If it runs good with a 625 it will run fine on a edelbrock 750
with a little fine tuning.