I have a 1973 stock 360 that i am going to put into a 1970 dart.  I was wanting to know what a good cam selection would be.  I have a 2500 rpm stall converter and i want a good street car.  What is the max lift i can use with the stock valve springs, and what would the compression ratio be on this year motor.  

The compression is going to be pretty low, Probably 8.5:1 at most.  I would stick to a pretty small cam like a com cams XE256 or XE262 at the most.  Either one is a good step from stock.  

I was told to use a comp magnum cam with a duration of 230/230 and a lift of .480 intake and exhaust. is this similar to the XE256 or X262?  i want the engine to have the classic musscle car thump if at all possible  

That cam will work [done it before] and run hard up top, but like adam was saying because of the low compression mixed with the cyl presure bleed off of the cam you will have poor low speed characteristics/gas mileage[worse than expected for the cam size that is].

This mix match would respond better with a 4spd, which is what we had when we did this= the customer and I that is.

I will say this If you really wanna run this cam at least have 3.91+ gears & a dual plane and 650 cfm [air speed] to help the motor out of it's slump.

BTW when we put that same cam +4* in a stock dish piston 77' 360 we ended up with 105-120psi cylinder pressure, with some holes less, not so great.  

This motor came out of a motor home and i have been told that vehicles larger than a 1/2 ton pickup didnt have as strict emissions regulations.  That said would this motor stand a chance of having a slightly higher compression ratio than a regular 73 360.  

Nope same compression ratio as the rest. Just didn't have the smog pump.  

Speaking of smog pump, did you guys know that chrysler was the last of the big 3 to be required by law to have to use a smog pump?  

Same with cats.