Russ,

I'd look at that H12 bullet lobe I mention above, single pattern on 110 in at 106. The key with manifolds is you #1 need Velocity so don't go too big on the duration and #2 you really can't get very much in the way of upper RPM scavenging so the better the intake tract works on its own, the better the motor is gonna pull up high. The RPM intake can do pretty well with filling that short stroke motor. More duration will kill torque, less will limit the RPM you need above the mid range.

Opinions always vary though