Index Match with Indirect

[MuppetReaper]

hi

I'm driving myself mad trying to make this formula reference a cell value instead of the "83" in the text

=INDEX('[workbook.xlsx]MCPOS'!$F$83:$ZZ$158,MATCH(LEFT(C7616,34),'[workbook.xlsx]MCPOS'!$E$83:$E$158,0),MATCH(A7616,'[workbook.xlsx]MCPOS'!$F$4:$ZZ$4,0))

the "83" should be replaced with the value in the cell that is in the next column where the row number could change.

I've tried an Indirect, but can't get it to work

I'm trying to make it something like this
=INDEX('[workbook.xlsx]MCPOS'!$F$&E7616&:$ZZ$158,MATCH(LEFT(C7616,34),'[workbook.xlsx]MCPOS'!$E$&E7616&:$E$158,0),MATCH(A7616,'[workbook.xlsx]MCPOS'!$F$4:$ZZ$4,0))

any suggestions please?

thanks