Well i have a 400 SBC (bore .030 over) and im going to put AFR 195 heads(65), flat top pistons and running pump gas (93 maybe 100) and being a power street car that i would prob take to the track prob 2 times a month and i was wondeirng would the XE284H cam be a good cam for that set up or should i take a step down to a XE274H

 

For a street/strip car that cam will work fine with those heads. Make sure you have enough compression (around 10:1 or so), that intake and exhaust are adequate and that your converter and rear gears are matched to work with it as well. It's a pretty lumpy cam- nothing you would ever want to daily drive, but for a weekend fun car it's a good choice.

With flattops and 65cc chambers you are going to be up around 11:1 compression. That might be a bit high for pump premium, even with that rather large cam. You don't want to have to retard the timing to stay out of detonation- much better to go a little lower on compression but be able to dial in spark advance that's opimum for making power.