Replacement Speaker for Peavey Vypyr 75w

Hello all,

I want to replace the speaker in my Peavey Vypyr 75w. Here is my amp: http://www.sweetwater.com/store/detail/Vypyr75/ (scroll down to Specifications). It does not have a speaker out jack like the tube versions.

Here's a back view of the amp: http://images02.olx.com.do/ui/11/07/15/1296189903_150160215_6-Peavey-Vypyr-75W-Sanpera-II-Footswitch-Santiago.jpg. The left cable is the power and the right cable is the footswitch.

The description says it houses a 12" custom voiced modeling speaker, this is not true. It has a 12" Peavey Blue Marvel. It is an 8ohm speaker. Here is the link to it: http://peavey.com/products/speakers/instspeakers/index.cfm/item/71540/BlueMarvel%26reg%3BClassic%26reg%3B-1238.cfm (Click on the Features tab.)

Here is a picture of the speaker housed in the amp: http://www.jlmebay.com/upload/814151c6b253e7a2a445c18660e7d131.JPG

The back of my amp says 75 Watts, 24.4V RMS, 8 Ohms. The back of the speaker says 8 Ohms.

I've never done a speaker swap and don't know anything about requirements, so I'm here looking for help choosing the right speaker. Ideally I would like to go with the 12" Veteran 30 - 60w speaker. But I'm not sure how the 60w of the speaker vs the 75w of my amp will work out. Would the 12" Retro 30 - 75w be a better choice?

Also, when I do purchase the speaker, do I need to get 8 ohms or 16 ohms?

Thanks for you help!