Bowl Blending

I just did this. Strictly an amateur mind you, but I streamlined the valve guide area cutting away some of the "shelf" where the valve stem protrudes and blending it down port. The tunnel between the valve guide and the side wall looked very narrow so I widened and smoothed that. I cut away some of the metal just under the valve seats so there wasn't a sharp edge. I did a little on the short turn to get a slightly greater radius. I took a little off the side wall where it narrows. The exhaust ports seemed to be worse than the intakes. I also unshrouded the valves a little on the deck. The easiest and quickest thing was port matching. After scribing it only took a half hour. About half of them had an extra 1/16" on one side that I removed. I think I spent 10-12 hours all together.
I just imagine myself being an air molecule rushing in (or out) and look for areas I would crash into.
I did this on my 318 (only 2-3 hrs using a Dremel) and improved the ET by a half second. I have no comparison for my 225 because I have not driven it yet because it wasn't running when I got it.