Too bad you could not see the beauty and simplicity and assume power of the blower motor.?
You have most of the parts required already.
Now you are going to buy a head and rework it?
Whats the differnce from porting a 234cfm dart shp head from porting a 920 head
to more than 234cfm
Typical is 240-250 ( non profession home porting 2.02x1.60) on the 920 head.
Yup thats the data I got on those heads 234cfm in 170ex.
I got my friend to port one port on his 920 heads. after showing him a few simple basics and the basic port form he was seeking. ( I showed him one of my finished 305 heads) He had never touched a cylinder head in his life. He spent 1.5 hours on a intake port. remember he has never touched a head before.
After 1 hour of his work I flow tested his 1 intake port with the stock 1.94 valve, stock OEM valve job, just his porting.
IT FLOWED 230 CFM.