He deals with new stuff from a distributor and he warrants it
Okay, that sounds like it's OEM then.
He told me that the 600 was the last athlon that had full speed cache he said but did not specify L1 or L2. He said due to that they were extrememly good over clockers
That part doesn't make any sense. If he was talking about level 1 cache, the Athlon 600 really doesn't stand above any of the other speed grades since many 550, 600, 650, or higher cores were used in even lower speed CPUs. (ex: a 650 core in a 500mhz Athlon)
If it's about level 2, he's wrong, it doesn't mean he was lying, he might not have known. The Athlon 600 has 300mhz level 2 cache. The Athlon 700 has 350mhz level 2 cache. Starting with the 750, the 1/2 cache speed was no longer used. That makes the 700 the CPU with the highest speed level 2 cache.
He says this chip being what it is can reach nearly 1 GHZ
That's a pretty high claim. If he meant the Thunderbird Athlons, or the Durons, then it's possible that the 600mhz chip can get to 900 or 1000 with good odds. But he told you the 600mhz chip was the highest speed with full speed cache? All the T-birds and Durons have full speed l1 and l2 cache.
I sound terribly redundant, but what this guy is telling you doesn't make much sense.