X-Head Flow Numbers - What to do

If you lay the exh short turn back too far..you will get better numbers, but you will move them way up in the lift range, and you really want the exh port to start moving air quick/soon in the early valve opening stage.
Go straight up from the seat and just kinda round the top of the turn, cut the guide flat with the roof, try to almost straighten the roof kink and of corse get the bowl in the 90's of the seat, also straighten the curved angles on the center ports around where they go around the head bolt. Dont widen or try to gasket match the exhaust port window any larger than the rest of the port... cause the gaskets r BIG and when you make the window bigger than the rest of the port... it slows the air 'hurts velocity' down and u lose flow, it becomes blockage for the air moving behind.

i would go for the 260cfm and try to work the exhaust ports more or cam it split pattern with added lift and duration on the exhaust, also consider while the exhaust actually picks up flow with a header tube...the int loses flow with an intake....so in actuality, the ratio you see on paper is not the running ratio ;)
flow it with an intake bolted on and see what you really have.lol