Looking at options for cone/"round tapered" type air filters. Not sure what the size is, but I know filtration is the most important thing, and flow rates are secondary. Last time I looked at this, I ended up liking Amsoil's EaAU filters, but that was years ago.
If anyone has any suggestions on brand or product line, please feel free to post up regardless of sizing; there may be some wiggle room on that anyway. Anything helps!