I ported a set of magnum heads about 3 years ago and spent about 50 hours doing it!!! cast iron dust everywhere!!! next time( if there is a next time) I will use a mask as I started catching a buzzz after breathing all that dust .... My hand was also numb for about 2 weeks after all the grinding with my dremel grinder... but I was pretty happy with the end result as all I did was clean up the bowls but they really needed lots of grinding as the valve guide bosses have so much extra meat around them.... I used these heads on a 360 and they ran very well.. I currently have them on a 70 318 with headers and this thing has so much more power it's unbelievable.... The tall, skinny ports give good velocity and these heads make a nice choice for a street/strip setup.. based on how well they work on my brothers 318, I would say these heads are a great choice for a 318 .... Eventually, These heads will make it to my 109K mile 5.2 Grand Cherokee and I just might throw a 4" crank at it as well TBF