I'm thinking about cutting 1-1.5 ft. off a 10.5ft. surf blank. The blank itself is rated for 20-40# braid, 2-6oz. lures, and is a 50/50 split. If I cut 1.5ft. off of the bottom, in effect making it a 9ft. rod, how will that affect it's action and rating? I'm thinking it'll make it faster, but how about what weight lures it can handle, or recommended lines? Will that change? Will I ruin the blank doing this?

The action will become much slower and overall fighting power will be reduced. Lure weight rating will decrease slightly.

..........

Use strapping tape to secure the reel where it would be if you cut off the rod butt and use strapping tape to secure the guides where you would put them. Let the butt hang out behind the reel; it won't affect the rod's action much. Take the rod out and test cast it, and pull on a weight with it - see how it works. I think you will agree with Tom's observations, but there's no accounting for taste.

A mock up as Phil suggest is the best way to go without permanently changing the blank. .

You will not ruin the blank if you cut it but you will be merely making a rod that is different than what it was originally intended.

The plus side is you could end up with a rod that meets or exceeds your expectations and the experience gained will make future builds more successful.

.