I have the YIO-390A3B6 on order from Vanís for my RV-8 set to deliver end of April. It will have stock Avstar/precision fuel injection. No mods should be required for the smooth bottom lower cowl with stock snorkel as used for the stock 200hp angle valve engine install. The other differences from the stock 200hp angle valve install include forward mounted prop governor, possibly using firewall mounted 13 row oil cooler and tight baffle to cowl clearance at the #2 cylinder. Still not sure about exhaust differences if any. I plan to order firewall fwd items as I go using Vanís packing lists for the 200hp angle valve firewall forward for the RV-8 and the YIO-390A3B6 firewall forward for the RV-14. Take this for what it is worth. Good luck!
RV-8 Tail completed, QB Fuselage in progress