Replicating the process Rex undertook, I get a result that, given the static weight distribution and a 0.35 coefficient, the coefficient would support 195 Hp at 160 mph. So, it would appear you would likely be power limited (to something less than 160 mph). (Was the 205 hp resulting from an engine dyno or chassis dyno?) Are tire size, gearing, and rev range compatible with this speed?
As far as biased ballast, I think Rex may have missed the part about the torque tube. However, lead or steel plates bolted into the footwells is a good location, that is, low in the car, if it is seen to be needed.
There is no clear and fast rule about advisable weight distribution. Each car will be different. The 55% you were told is probably the result of not wanting to get too much in the rear which could lead to aero instability. It depends on the car’s aerodynamics and how close to instability you are comfortable with. Roadster drivers explore this frontier all the time.
Also bear in mind that due to aero drag of about 458 lb, there will be some front-to-rear weight transfer which would help load the rear, however, the rear is liable to be generating some lift, which would detract from the rear loading.
Interested:
To your first question, it was an engine dyno, so I'll also suffer parasitic driveline losses that may be in the 20+ RWHP range
Re: tire size and gearing, the engines' max torque and HP output 8,200 RPM's equates to 160 MPH with the gearing and tire diameters in use. That is ,of course, stricly calculational and doesn't mean the engine will be capable of achieving that RPM at that speeds' resistance.
Rick
P.S. BTW I want to thank all of you for your input. Having helped lots of newbie road racers over the years, I know it can be trying to educate the uneducated!