You're dealing with a fairly stock motor here. I'll assume it's the original 305 so probably 8.6:1 on the compression and I'd also assume that you've got a few miles on this motor. In all likelihood, the cam you're looking at would be a colossal waste of money. Without trying to sound harsh - what exactly are you looking to do? A bigger (than stock) cam is almost always a disaster unless it's part of a system, i.e., with the heads, perhaps new pistons, intake, headers, etc..

If you're dead set on a replacement cam, the Lunati 60100 is more along the lines of what you should look to for stock motor. It's 250/256 degree duration and .437/.454 lift is about all the stock heads will be able to handle and .454 lift may be too much for your springs (as mentioned above).

As to a double pumper - well, sounds cool to say you have one, but most people have no idea what the double pumper brings to the equation. The 600cfm you've got probably doesn't perform as well as the Q-jet that the 305's came with when optioned with a 4 barrel.

If you really want to have some grunt and snap, start this process from scratch. Sit down with a piece of paper and determine what you'd like to have in terms of horse power and torque. Then select the components and build the engine on paper - costing out the process. If you ask, there are several here who will be more than willing to help, but we tend to take the parochial approach and consider the engine in it's entire form and not just a piece here-and-there. Bolting on chrome valve covers or a chrome alternator is cool and fun, but a piece meal approach to the guts of the motor will just give you a lot of trouble.

I know it's sometimes hard to wait until you have the funds to do "the whole engine" but believe me - it's better to do it that way and far more rewarding as you'll have a quality end product. Delayed gratification is a lost concept these days and we tend to want to rush through every aspect of our lives - including our hot rodding. It's supposed to be fun, but we need to remember that the "demands of the services or the importance of the task are never so great that we can not take the time to do it right."

Just my two cents - but I've been where you are. Other will, I'm sure chime in..

Regards,
Glenn