Firstly, good choice, the PCE version is a much nicer tartan IMO. What you now need to consider is what shades you want/prefer. As an example, here are four specimens of the tartan dating from c1790-1840, all woven by Wilsons of Bannockburn and all visually different.

Wilsons - PCE specimens.jpg

The records at the Scottish Register are a complete mess, the problem is that they don't the expertise to sort them out and no money to pay for the work (quite a serious undertaking) to be done. The Stewart entries are a prime example of the chaos. As an aside, they do include the PCE tartan - see entries 1371 and 1373.