In general the heads I worked with ( small block Chevy and Ford Windsor and Cleveland) liked th have the guide removed from the port, the bowl area below the valve opened up as far as possible, and the largest valve possible installed. Both the intake and exhaust liked the port raised, especially the exhaust. The exhaust also liked a rounded top.

On a street car I would not remove the guide completely. Just narrow it and maybe shorten it. When you are working on the guide remember the direction of flow and that the most efficient airflow shape is a teardrop.

Smoothing the sharp ridges will increase the smoothness of the flow but will it be worth the effort? A good machine shop should have a Serdi type head machine that will cut all the seat angles all at once with a cutter. There are cutters available that cut a radiused seat with no more effort or time that a stock valve job. If your machine shop does not have a seat cutter for this, offer to buy the cutter blade and bring it with you when you get your heads done.

Probably the most effective head work and some of the cheapest head work is what most shops call the stage one. they clean up the bowl area and sometimes install larger valves. If your machinist says just bolt them on I would seriously consider finding a machinist who has some understanding of what high performance is.