hey whats up.ive been porting heads for 20 years and built several motors for customers using these heads.not gonna get into what i know due to people on here thinking you have to spend money with people that are on tv and such. this and 049 is the most common head used for a performance build.these heads are capable of 700 plus hp as ive dynoed several.with the right cam,comp,etc. of course. the stock 2.07 in. valve is the main restriction in these heads. depending on what you have for a cam and comp,and stall conv., usually the first step on these that i recommend is going for a 2.19 in 1.88 ex. valve install with a 5 angle.this opens up the pocket to a better percentage of what the port is seeing for airflow. this reply could go on forever as everybodies application is diff. i can give you some advice but might i add that you can f*** heads up in a hurry if you dont know where to go with it.trust me ive fixed several over the years.some not fixable. might have had your work done already who knows lol.