My garage's fascia has rotted to the point where it's peeling away and providing an entrance for critters or otherwise unwelcome visitors. I have sized up the material originally used and did some scouting for replacements at my local home depot. The dimensions of the boards I'm looking to replace (6 inches high, 1/2 inch deep, and 8 feet long) are not readily available, apparently. (See attached photos for reference (pardon the poor focus).)

I realize that there are plenty of size options for this type of replacement; the reason I'm so intent on finding this particular size is that I only need (and want) to replace the one problematic side of the garage -- in order to have the corners meet squarely all fascia boards need to be similarly sized (again see photos for reference).

It's worth noting that the three other sides are in relatively good shape and therefore I don't want to replace all four sides.

I've already made an in-store trip to Home Depot and have scoured the internet for boards matching my sizing criteria, to no avail. Are there specific sources I ought to be looking at to find my desired measurements? Or should I bite the bullet and but an oversized board and then cut it down to my dimensions? Are there other reasonable options I'm not considering?

Thanks in advance for your feedback. First time poster, very much looking forward to your collective experience and expertise.