A few ways you can go about it, in my opinion.
1) Look up the return on WoO VP Calculator and use the optimal strategy given. That will, of course, be the highest return and most optimal way of playing. WoO gives a 1.5229% player edge, not taking into account the meter rate.
2) If you don't want to make the changes in strategy, you'll be giving up some % in edge, since optimal strategy is more aggressive with royals. To calculate the return using your current strategy, look up the frequency distribution per hand using WoO VP Calculator. To get a more accurate frequency distribution, divide payoff by return (since only 2 decimals are shown in frequency distribution on WoO chart). The return is payoff divided by frequency. So now all you have to do, is change the payoffs accordingly (2000, 50, 80, 40, 25, 7, 5, 4, 3, 2, 1), divide each of those numbers by their frequency to get the return per hand, then add up all the returns, and that'll be the total return on the game using that strategy. To approximate the variance, do (payoff ^ 2 ) / frequency for the new royal payoff. Subtract the normal RF variance (15.87) from the total variance (20.90), then add the new RF variance (~99.42), to get the total variance of the play. The difference in variance between 8 credit FH and 7 credit FH is negligible. I did not take into effect the meter rate and how that effects edge.
I did the calculation quickly (check my work?), but if you use optimal 8/5 BP strategy on this game (2000 credit royal, 7 credit FH, 5 credit flush), your edge is 0.997175%. The return is 1.00997175.
Remember, variance can be a monster! The play only succeeds if you hit the royal (1 in 40,233 hands), and can take 2 or even 3 royal cycles (~80,000 to 120,000 hands) before hitting the royal. Be careful!