Rampant colt OK in rear of slide?

Hi,
I want to buy a Colt 1911 made in 1918 SN# 288XXX. There's a rampant colt stamped at the rear of the slide behind the grasping grooves and Clawson's book says that the rampant colt stamp switched from the rear to the middle of the slide around SN 275,000.
This Colt has about 60% finish remaining and the grips look just as worn. The slide looks just like the rest of the piece so it really doesn't look like the slide was switched, at least not before it saw use.
Anyway, I suppose the price should be affected if the rampant colt in the rear of the slide 100% can't be on a 288,XXX slide.
Any help is appreciated, as I am more into Garands and have no books on 1911's.
Thanks.

I believe Clawson indicates that the marking was moved in the 275000 to 290000 range. It was a gradual changeover. Yours is probably correct if finish and wear are close.

Thanks! I will be buying it either way but the prices are all over the place in various websites.
It's a shooter. Lots of wear everywhere. 60% may be a generous extimate on the finish after seeing the 70% one in the Blue Book.