Here’s a few pics of a cross flow scavenging setup. The ports with the black around them are the exhaust ports, the other square ports are induction ports and the little thin slit ports are called PDP ports. (Perry Directional Porting). This is from a German HB .40 PDP Blitz. Liner is chromed and it uses a narrow piston ring on an aluminum piston; conrod is forged aluminum; not cast and not machined from billet.

Old school cross flow engines used a Meehanite piston in a (usually) hardened steel liner. Some guys used steel pistons in steel liners too.