From what I see the lump on the port flow is too straighten the flow before it hits the valve head.So the port floor is raised by the lump.On a later L series head,once the divider between the ports is removed,you have room to work on the port floor.On a 235-261 with it's 3 intake ports there really isn't room to get in there very easily. Modern porting theory is also concerned with port flow velocity,maybe more so than all out flow numbers. For example with the Chevy V-8 guys it's the newer Vortec type head that pretty much is the best buy for the money.Not the biggest ports but better flow and velocity. Buy a cracked Vortec head,they do crack,lol,and examine the port design,see if it can be applied to the 235 head.Or look at a late LS V-8 engine with it's goofy shaped intake ports. Or perhaps a head swap,maybe like the welded together V-8 heads used on the L series engines.
