Sounds good. I was going to grab a spectre length as well. Price sold me on the carbine one I got. I love the diamond design on the handguard. It's large enough as well without being too bulky.
Even with the barrel you have I think the marker would look nice. It'd have the "rifle length" appearance without the rifle length size, which is much longer than the spectre sized handguard. plenty of room for sensible gear as well.
Super freak and an apex tip? Do it. Get some footage. I'd like to see the apex in action. As well as some sr-1 action