INDEX MATCH using partial "Begins With" lookup

[Quinapalus]

I'm trying to organise FIX message data using Excel. The challenge here is that different types of FIX message are comprised of different numbers of component tags and not always in the same order; for example (XXXX denotes sensitive values):

[TABLE="width: 500"]
<tbody>[TR]
[TD][/TD]
[TD]A
[/TD]
[TD]B
[/TD]
[TD]C
[/TD]
[TD]D
[/TD]
[TD]E
[/TD]
[TD]F
[/TD]
[TD]G
[/TD]
[TD]H
[/TD]
[/TR]
[TR]
[TD]1
[/TD]
[TD]FIDEXP
[/TD]
[TD]00216793249FILO1
[/TD]
[TD]OUT
[/TD]
[TD]Heartbeat
[/TD]
[TD]49=XXXX
[/TD]
[TD]56=FIDESSA
[/TD]
[TD]43=N
[/TD]
[TD]34=1410
[/TD]
[/TR]
[TR]
[TD]2
[/TD]
[TD]FIDEXP
[/TD]
[TD]
[TABLE="width: 126"]
<tbody>[TR]
[TD]00216793250FILO1
[/TD]
[/TR]
</tbody>[/TABLE]
[TABLE="width: 126"]
<tbody>[TR]
[TD][/TD]
[/TR]
</tbody>[/TABLE]
[/TD]
[TD]IN
[/TD]
[TD]Execution Report
[/TD]
[TD]115=XXXX
[/TD]
[TD]34=1774
[/TD]
[TD]49=FIDESSA
[/TD]
[TD]56=XXXX
[/TD]
[/TR]
</tbody>[/TABLE]

In order to carry out analysis on the data, I would like to re-organise the Tag data into a cohesive order. I have been trying to do this by creating a second sheet in the workbook that has the Tag prefixes as a header row with the intention of using these a lookup values for relative ranges in the original sheet. The output that I am trying to achieve would look like this:

[TABLE="width: 600"]
<tbody>[TR]
[TD][/TD]
[TD]A
[/TD]
[TD]B
[/TD]
[TD]C
[/TD]
[TD]D
[/TD]
[TD]E
[/TD]
[TD]F
[/TD]
[TD]G
[/TD]
[TD]H
[/TD]
[TD]I
[/TD]
[TD]J
[/TD]
[TD]K
[/TD]
[TD]L
[/TD]
[TD]M
[/TD]
[TD]N
[/TD]
[TD]O
[/TD]
[TD]P
[/TD]
[TD]Q
[/TD]
[TD]R
[/TD]
[TD]S
[/TD]
[TD]T
[/TD]
[TD]U
[/TD]
[TD]V
[/TD]
[TD]W
[/TD]
[TD]...
[/TD]
[TD]DK
[/TD]
[/TR]
[TR]
[TD]1
[/TD]
[TD]34=
[/TD]
[TD]35=
[/TD]
[TD]36=
[/TD]
[TD]37=
[/TD]
[TD]38=
[/TD]
[TD]39=
[/TD]
[TD]40=
[/TD]
[TD]41=
[/TD]
[TD]42=
[/TD]
[TD]43=
[/TD]
[TD]44=
[/TD]
[TD]45=
[/TD]
[TD]46=
[/TD]
[TD]47=
[/TD]
[TD]48=
[/TD]
[TD]49=
[/TD]
[TD]50=
[/TD]
[TD]51=
[/TD]
[TD]52=
[/TD]
[TD]53=
[/TD]
[TD]54=
[/TD]
[TD]55=
[/TD]
[TD]56=
[/TD]
[TD]...
[/TD]
[TD]115=
[/TD]
[/TR]
[TR]
[TD]2
[/TD]
[TD]34=1410
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]43=N
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]49=XXX
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]56=FIDESSA
[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]3
[/TD]
[TD]34=1774
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]49=FIDESSA
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]56=XXXX
[/TD]
[TD][/TD]
[TD]115=XXXX
[/TD]
[/TR]
</tbody>[/TABLE]

For each cell in the second sheet, I want to define the corresponding row in the first sheet as an array, then search within that array to find a value that begins with the value of the column header and return that value the cell.

I have tried to achieve this using various combinations of INDEX, MATCH and SEARCH in Array Formulae, but have not been able to put together anything that works consistently.

Grateful for any advice on this