The 2 year correlation close-on-close is 95.6%
To currency adjust the contracts at today's settle of $70,130 the ratio is 1 TF : 1.28 YM
To adjust for volatility, the ratio is 1 TF : 1.63 YM
The best way to beta correct for these contracts IMO is to monetize the 20 Day Average Daily Trading Ranges for each of the contracts, and Voila !