I know of one case where an SLP spring broke with a MMS 224 cam.

I'd check out the REV-1116 dual springs for unmachined stock heads. Thunder Racing sells them. I think the REV duals will probably hold up better than the SLP's.

 

Are the SLP springs any good? I'm a little worried about spring choice with the comp cams breakage and all. I will only be able to change springs on the car as the heads won't be coming off. I just whant to change them and forget about it.