Dude,
I got a Downey smog legal header for my 40, another Downey header on my Pig.
You will need some kind of grinder. Expect that with any header. An angle grinder will get it done, a dremel is occasionally useful.
Wrestling the header into place can be frustrating.
You need a new exhaust pipe, of course, but driving to the shop with uncorked headers is really, really fun. Keep a copy of the yellow pages with you, so when the officer pulls you over, you can point to the page opened to "muffler shops".
I just use one gasket, a good one. Get a new set of official Toyota studs and washers and nuts. And a few spares.
On the scale of difficulty...on a 60?...(I've only done my 40 & 55)...your first time? a weekend (I've done it in a day). Taking your time.. I'd rate it a few bananas just due to the tight spaces and stuff.