Everyone has their own priorities when testing, but to my way of thinking....... To not do a back to back test where the only thing changed is the heads, really just muddies the waters about how the heads themselves compare.

Test the 240 heads with the TF intake and the 4150 carb of your choice..... Get a number.
Put the intake and carb back on the 270 heads as the starting point..... Get a number.
That's a back to back comparison without anything else skewing the results.