I have created a spreadsheet using the assigned weightings in the OP.
The formula works as (Test Ranking x 2) + (ODI Ranking x 1.5) + T20 Ranking = Batsmen's multi-format value.
This means the best players will have the lowest total values.
This is obviously not perfect as it only takes into account rankings not ratings but I may work on something more complex in the future.
(Note, where a player is not ranked in the top 100 - all that's provided by ICC - they are given a ranking of 101 for purposes of the formula)
Remember the less points the better!
Using this formula the top 10 is as follows.
Let me know if you'd like to have the weightings altered and see how that changes the rankings.
Have done most players if there are any requests for someones total 'points'.
Note: Warner & Smith currently sit at 222.5 & 260.5 pts respectively.
Pre- ban they would have been 36.5 & 122.5 leaving Warner in 3rd and Smith in 9th.