Cam sizing

Its so hard to decide lol im thinking about getting the cam that moturbopar posted http://www.summitracing.com/parts/HRS-CL710991-08/ with new valve springs. And i probably wont use the 360 heads or intake i just got them on a trade and didnt know if the would be better or not. I plan on building a 360 in the winter or so but i just wanna pick up my 318 a little bit and run it at monster mopar also! How hard is it to change the springs when there on the motor? I have a valve spring compressor that i can do it with the heads on the motor but have never tried it like that. Thanks!