When you build a wheel the spokes deform to fit the hub, using old spokes on a new wheel build makes a weaker wheel. Also the length might not be correct, use the UDC spoke calculator to check. A drop of oil on the spoke threads would be fine, it’s just to decrease the torque applied to the spoke as the nipple is turned.
Looks like you’re going to need to measure up your rim and enter the data in to the calculator, unless you can find them online. Having said that, just ran the caculator with the dx32 rim, and both hubs, and the spoke legnth comes out within .3 mm so your old spokes should be the right length. If you can;t work out it just ask Roger, he prob has the data for your rim seeing as he sold it to you.
after breaking my hub i just used the original spokes and my wheel seems fine i have droped from some farily big hights and not even a sound, i didnt look into how much new spokes would be though, if they dont cost much you might as well replace them i wouldnt like to have to redo it all over again
Yeah to be frank when I upgraded from a nimbus to KH hub on my nimbus uni I used the same spokes and never had any problems, particulalry because it’s a muni not a trials uni. New spokes cost £15 from UDC.