Yes. Cast iron heads can just have the seat machines right in situ. Guides, another story. I have a bronze valve guide liner kit for most 1mm increments, +/-.01mm ball reamers. BMW, MB, VAG actually uses bronze OEM, GM, Ford and other USDM use hardened tool steel.
Hmm. For some reason, went in the shop storage to poke around and realized there's a Subaru sp170 in there. Two old pressure washers, although one is a vertical shaft. Stripped down with the cylinder exposed, might just fit the bill (pic stole from interwebz)
I feel the OHC looks too modern. Did some poking around on eBay and found some vintage Briggs f-heads (model 09A413) for very reasonable prices. Most are "5hp" which are actually 3.5, should do the trick.
STARTS EASILY, RUNS EXCELLENT. BRIGGS MODEL 09A413. We have thoroughly degreased & power washed this really nice little engine, and it is in really good condition. Or use it to replace that blown up snowblower engine from last season.