To give you an idea here's some factory specs


IA EA I50 E50 LIFT LOBE
Pontiac 9779066 273 282 200 210 .410 .410 111

Pontiac 9779067 273 289 200 213 .410 .410 114

Pontiac 9779068 288 302 212 225 .410 .410 116 RAI, HO

Pontiac 9785744 301 313 224 236 .410 .410 119 RA III

Pontiac 9794041 308 320 231 240 .470 .470 114 RA II & IV


looking at those now you'd probably be happy staying away from anything like the II, III or IV, the RA I cam was already in use as anything HO in 67 so that's what they used, it's only slightly radical, fairly smooth idle, anything like the O66 or 67 will be good too