Top poppet intake, bottom rotary valve:

 There have been many attempts at using rotary valves in internal combustion 
engines.  Some have worked, sort of, but once the problems of heat, sealing, 
and wear were eliminated, most of the rotary valves don't flow very well, even 
compared to an ordinary poppet valve.

 You might try putting a rotary valve in the side of the block, down where the 
piston would cover it unless near Bottom Dead Center, like a two stroke 
exhaust port...

a) the rotary valve would see a maximum of 300PSI, mostly less.  It 
   would never see primary combustion pressure, nor would it see 
   knock, etc.  It could run in a water jacketed housing with no 
   high pressure loads. 

b) port in bottom of cylinder would bleed off about 90% of
   cylinder pressure, according to usual indicator diagrams 

c) if you used a rotary valve at the bottom you could make the 
   ports much larger, time the rotary valve at 1/2 crank speed and 
   you wouldn't contaminate the intake charge too much (just what 
   was in the port area before the valve). 

d) the direction of scavenging would be primarily down