Yes, I too have built many a small block chevy, gasket set $50. 911 top end gasket kit $200, there is a big difference.
If you know how to do it, and you want it done right, do it yourself. If you don't know how to do it, it's time to learn. I don't know if I ever been satisfied with someone else's work, and I'm not pickey.
I had never seen a flat 6, before I bought mine. Armed with Bruce Anderson's book and the Haynes book, I was very successful at doing a top-end job on my 3.0, all by myself. Bruce's book came into play concerning cam timing, I don't remember the specs, but I advanced it about 4 degrees, what ever the great porsche compromise was.
Pulled the guides, and installed new ones. Took the heads to a shop, and had the guides reemed, and the valves and seats cut. I think it was in the $60 range for the shop ($2 a valve, $3 a seat). Had to replace two head studs, snaped in the center, how lucky could I get, no thread-certs or block repair. Couldn't afford the carrera tensioners, but did install the solid aluminum slug inserts, that will buy me time for the carrera's. All in all I spent about $1k, and all is fine. I made a parts list, and when I was ready to order I received a 20% off coupon from Performance Products. This saved me $ also.
If you've built a SBC you can build a 3.0. Just be patient, keep everything clean like you are doing open heart surgery on yourself.
If you get hung up on something put it on the bbs and you will get some quality advise.
The Haynes book worked for me, but I now have the Bentley book, and would recommend you get it. You can get the SC book here for $84.20.
http://www.bimmerparts.com/
I photo-copied mine and placed all of the copies in plastic sheet protectors, and binders. 6 binders. I can keep the original one clean and in the house, and the plastic coated one in the garage.
The Bentley book can answer just about anything on the SC.
Thousands of men and probably even some women have been successful rebuilding the flat 6, and I'm sure you can too. Just don't ever say "I hope I did that right", if in doubt check it out, and make sure you did that right.
Providing my own labor, I would certainly think I could rebuild my whole engine for $2500-$3000. It's just time consuming working on it in the evenings, but it makes it easy to be patient.
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GT911
GordonTaylor@ev1.net
'81 911 SC very very fun
'84 BMW 318i very very economical