Since I have the Dyke in the shop and a ‘new’ Renesis’ sitting right by it, time for me to seriously consider all the new things. 

George

Reworking the right strake to accept a radiator instead of the oil cooler would be a pain, and then you'd have to work the oil cooler into the cowl, which would be easier, but still significant work.  The benefit would be much shorter oil lines, no firewall penetration for oil, and a full length K&W duct for both radiators.

Going plugs up would require a new motor mount, a remote oil reservoir, new exhaust, and a new intake manifold.  But....  you'd be dumping that exhaust heat sooner and the intake manifold would be closer to the 21" optimum runner length. (It is 21 right?  Been a long time.) Since you're going with the Renesis, the new intake, motor mount, and exhaust are already a given.

For a new blower shroud, I'd either move the exit to coincide with the starter, or move the starter to coincide with the exit.  For a centrifugal blower, you want a constantly increasing cross-section.  What I did got compromised by conflicts with the starter installation.

If you switch out the gearbox, note that I'm pretty sure I offset the tail for a normal rotation prop.  Not sure if that is on your radar, but....