Heat riser block off plates

Do I really need to use the heat riser block off plates or can I leave them open. I have had a lot of exhaust issues and am wantin to get my car back on the road but I am lacking the block off plates. It doesnt look like I really need them but I wanted to ask.Scott

On other question when I get rid of my heat boxes what do I do to cover thr holes in my shroud.

Scott where do you live. The reason I'm asking is that I have a new doghouse style fan shroud without the holes for the heater boxes. I would sell it for a good price, but the shipping costs may make it not worth the effort. That's if you wanted to go that route and switch shrouds. If you keep your shroud you may be able to buy plugs for it. By the way, I live in British Columbia, Canada.
Ron