Smithsax, the online scots dictionary is a good source.
http://www.scots-online.org/dictionary/
I looked up 'safe' just now, and it returns 'siccar'. Then a check in TCD reveals 'sicker'. An alternative 2-step process is to use the google 'translate to' facility, but to translate English to Danish or Norwegian. In this case both return 'sikker' : which is probably close enough to get you there, and is no coincidence, since northern Scotland is more aligned, geographically and culturally, with Norway than with England.