0.3% or 0.8%

I am lucky enough to find a great game that has 0.3% positive ev off-the-top and 0.5% rebate on my winnings, no cheating, I believe. I plan to flat bet the game with $200,000 bakroll unless at minus 10 rc. Question: Should I bet $300 or $800 at halfKelly? Thanks for responses. No, I will not tell where.....