here's a silly question...
 

a buddy of mine has a stack of old O2 bottles he found in a house, they look like 5-8lb bottles at best. setting the size aside, can they be used for Nitrous with the proper fittings?

I honestly wouldn't take the chance to use them for nitrous...however i bet they'd work for a pusher set up.

Your in houston for christs sake walk 2 blocks to a speed shop and buy a n2o bottle lol.

They might work for nitrous bottle with a different valve in there but no one makes a siphon tube for that size bottle unless they are 5lb bottles. Also you need to find out what thread that bottle is to even see if a nitrous valve will work in there. The biggest problem you will find is someone that will fill that style of bottle with nitorus. Some companies are leary on filling a bottle thats not a specific nitorus bottle.

Peronsally i wouldn't waste the time nor money tring to make those work. Pluss they might be out of certification and need to be recertified.

Sell them for scrap and put the money towards a new bottle. You might be able to sell them to a medical company and get even more money for them.

yeh mom works for MD Anderson so i bet i could get something decent for them

That would be your best bet....