I recently rebuilt a 408 stroker motor and now that it is running I am noticing an oil leak that I believe is coming from the front of the intake gasket. Oil pools at the top of the timing chain cover. I am wondering what could be causing this so your suggestions are appreciated.

Things I have considered so far:
1. engine not breathing/venting well
2. intake was milled and may not have the proper fit. The gasket does not appear bulged out and engine builder pays close attention to details
3. your thoughts here...

thanks!