What are these blades on the engine cowling of a Wittman Tailwind?
After calling the Florida Air Museum, I have discovered that this seems to be a local mystery to the employees at the facility, as well. The museum’s director assumed that they “were an attempt to counteract P-factor or torque. Something to do with balancing required power.”
Since this was little help, I did some more digging and decided that the “blades” on this Wittman seemed to function as adjustable strakes - albeit located far from any control surface and of dubious utility.
Finally, I discovered that there have been numerous experiments performed with ‘Actuated Forebody Strakes’ aimed at controlling forebody vortices as a means of complementing thrust vectoring. Additionally, a NASA study found that a large increase in yawing moment may be brought about through the manipulation of actuated forebody strakes.
In every case that I could find, the tests were concerned with fighter jet aircraft operating at high angles of attack, but it is conceivable that the owner of this Wittman W-8 was attempting to implement some of the same advantages here.
Here are the abstracts to the vortex thrust vectoring and NASA yawing moment studies:

The desirability to enhance the controllability of fighter aircraft at high angles of attack, particularly yaw control, has fostered an interest in both vectored thrust and active control of forebody vortices... The methods investigated include pneumatic or blowing techniques using surface mounted jets and slots, surface suction, variable-height deployable strakes, and rotatable-tip strakes. Flow visualization, and force and moment measurements have shown that all of the methods are effective at manipulating the forebody vortices over a wide range of angles-of-attack and sideslip, primarily through control over flow separation on the surface of the forebody. All are most effective when applied near the forebody tip.


Extensive pressure measurements and off-surface flow visualization were obtained on the forebody and strakes of the NASA F-18 High Alpha Research Vehicle (HARV) equipped with actuated forebody strakes. Forebody yawing moments were obtained by integrating the circumferential pressures on the forebody and strakes. Results show that large yawing moments can be generated with forebody strakes. At angles of attack greater than 40°, deflecting one strake at a time resulted in a forebody yawing moment control reversal for small strake deflection angles. At α = 40° and 50°, deflecting the strakes differentially about a 20° symmetric strake deployment eliminated the control reversal and produced a near linear variation of forebody yawing moment with differential strake deflection. At α = 50° and for 0° and 20° symmetric strake deployments, a larger forebody yawing moment was generated by the forward fuselage (between the radome and the apex of the leading-edge extensions), than on the radome where the actuated forebody strakes were located.

References:
Malcolm, G., &amp; Ng, T. (1990). Forebody Vortex Control as a Complement to Thrust Vectoring. SAE Transactions, 99, 1515-1543. Retrieved August 16, 2020, from Journal of Aerospace
Fischer, D.F., Muriel, D.G., &amp; Lanser, W.R. (1996). Effect of actuated forebody strakes on the forebody aerodynamics of the NASA F-18 HARV. NASA Technical Memorandum 4774. Retrieved from NASA.gov