You should have everything cleaned really well, then use precision mics to measure the crank for wear and/or taper, the bores, the pistons, valve stems, etc. Same with the rods.
What I don't know if is you can find bearings for those rods - have never built a canadian flathead engine like that. As I stated in my previous post, you may need to switch over to late 49-53 rods and later bearings. If you end up needing new rods, buy the new ones from SoCal - will save you money in the end.
Once everything is cleaned, inspected and accurately measured, then you'll have a better idea on your options. You might be able to ball-hone the bores, polish the crank, throw in a set of later rods, put in new bearings, do a valve job, buy a gasket set and have a low-buck rebuild . . . time will tell.
Question: You mentioned you were going to "grind the valve seats" -- so you have the necessary equipment and knowledge? What are you pondering here?
Valve Clearances: Given your engine, when you redo the seats and the valves, the clearances will get tighter - so the valve stems are ground on a valve machine. Most valve grinding machines have two wheels - one for the valve angles/faces and one for butting the stems. With that said - I highly recommend you have an
experienced flathead shop do the complete valve job. Most "Normal" shops will not have the seat pilot for a flathead and you should not use a valve guide for a pilot -- so this is a question I'd be asking as well. Valve jobs on flatheads are a bit time consuming - so expect to pay a bit more than on a set of OHV heads.
Here is a Kwik-Way One: (The Sioux one is double-ended - picks up the lifter bore as well).
Best of luck,
D