If you can't get the required adapter, I guess it's the only option. It seems you're having about as much luck as I had a few weeks ago. I'm sure you could get them on Ebay for a few dollars.
I went through: Ordered two E8400s, before they arrived, my P5K died from a bad flash, then my Q6600 was sold on Ebay. So I ordered a new mobo, the new mobo didn't have the required BIOS to support the E8400, I didn't have my Q6600 so I had to obtain an E2140 which took about a week to arrive so I could flash the BIOS. When I'd flashed the BIOS, and dropped my E8400s in, both turned out to be duds needing way too much voltage to overclock.
But now things have got better, my P5K is back, my E3110 is here, and some unlucky people now own my E8400s.
Anyway, that's just my story.