Welcome to Ireland Reaching Out!
The RC parish for Killofin is Kilmurry McMahon. Unfortunately the baptismal records for that parish start in 1845 and marriages start in 1837. So a baptismal record for Martin would not be available. Civil registration did not begin until 1864. Here is a link to the parish register http://registers.nli.ie/parishes/0794
The James that you found could well be the father of Martin but there is no way to make the connection.
You may want to consider autosomal DNA testing. Possibly you will match someone who has more information on the Russell family.
Let me know if you have questions.