The AFP fuel servo can be mounted in any orientation. Have you considered a Superior cold air sump to mount it horizontally?
I mounted my AFP servo horizontally with the existing vertical sump hoping for more ram air effect but not sure it helps. Likely better than the snorkel, though.
This was taken during the build last year and replaced the x-over to trombone exhaust for clearance. Not sure your -4 has enough room for this. Don at AFP has the parts to do it.

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Ray
RV-7A - Slider - N495KL - First flt 27 Jan 17
O-360-A4M w/ AFP FM-150 FI, Dual PMags, Vetterman Trombone Exh, SkyTech starter, BandC Alt (PP failed after 226 hrs)
Catto 3 blade NLE, FlightLines Interior, James cowl, plenum & intake, Anti-Splat -14 seat mod and nose gear support
All lines by TSFlightLines (aka Hoser)
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