You did not screw up at all. An engine is an engine and a 351 is an great choice. The only problem with a Cleveland, as some have already stated, is the lack of aftermarket parts. But it is no more of a challenge than finding parts for a 427 side oiler. You should have a great mill when you are done.
There are more parts showing up every day for this engine. Here are some examples
396c Stroker Kit
http://www.flatlanderracing.com/stroker351c396.html
408c Stroker Kits
http://www.flatlanderracing.com/stroker351c408.html
Intake Manifolds
http://www.edelbrock.com/automotive/man_ford_351c.html
Performer RPM
Torqure
Victor Yates
Victor Y
Heads
http://www.edelbrock.com/automotive/headford.html
http://www.jason.fletcher.net/tech/f.../cleveland.htm
Victor (race)
Victor Chapman (race)
Cleveland
Aussie Cleveland
Cams
Crane Power Max Hydraulics
http://www.cranecams.com/master/apps/ford37.htm
Crane Power Max Solid Roller
http://www.cranecams.com/master/apps/ford43.htm
Crane Power Max Mechnical Lifter
http://www.cranecams.com/master/apps/ford42.htm
as long as you components are reasonably matched, you will have a great engine.
Andy