Seems like the 068 is proven, however I wonder why more people don't recommend the 066 or 067 since the OP wants to cruise at 1800rpm. Their shorter duration brings the peak torq down quite a bit. I would still vote for the 068. Seems like a nice compromise between performance and economy.
I couldn't find any more data on Jim H using the 067 cam.
http://www.dapa.org/building-a-stron...iac-camshafts/
http://forums.maxperformanceinc.com/...hlight=068+455