based on the original listed flow numbers its nothing to get excited about,,, a "canted valve" type head should flow 40+cfm more than the numbers listed on the intake and 30-40 more on the exh

a symetrical port head means a common int and exh port, spaced at bore spacing... a spread port head means ports are spaced apart more than factory. id imagine if its a real spread port head then it may be like a tunnel port type head with a pushrod sleeve going through the center of the port