340 Max HP Potential with X/J heads?

I will let you know how it turns out. I am accumulating parts for my winter time project. la318-->390 J head unported with a XE275HL HFT Cam SCR yet to be determined based on actual CC size but estimate with 70CC Chamber will be 10.6:1. As @justinp61 said tho... Just a street motor in a truck...