valve spring question

Ok motor gurus I have a pair of J heads that had been rebuilt when I bought them. I purchased a mutha thumper cam to put in my 340. I went to install the vale springs that came with the cam but the inside spring will not go over the valve seal. Now for the question, the springs that were on the heads (going by the diameter measurements that I took) are mopar performance springs part # P4120249 good for .430-.500 lift so will these be adequate and compatible with the cam mentioned.
Thanks for any and all recommendations.