The first two dates you mentioned (born abt 1730 & married abt 1754) are generally accepted by Feland researchers although I have seen no firm documentation to support them.
The third date, 1783/4, was the time period when Thomas Feland, JR. was killed (family tradition says he was killed by indians but again no firm documentation). Thomas, Sr. did not die until some time after 1787.
Thomas, Sr (or Thomas I & II as I sometimes refer to them because there is no documentation spelling out either "Jr" or "II"..only one court document refering to them as Thomas...the younger and Thomas...the elder) married Elizabeth, maiden name unknown, and they had eight (8) children: Thomas, Jr b. 1755 James, b. 1760 Sally, b. 1761 Jane, b. 1763 Andrew, b. 1766 Samuel, b. 1775 John, b. 1775 Elizabeth, (Betty, Betsy)b. 1778
Thomas, Jr married Catherine Miller in Campbell Co., Va (no proof) and had eight children between 1771 and abt 1780 (all born in Virginia): William, b. 1771 Elizabeth, b. 1772 Joseph S., b. 1773 James, b. 1774 Thomas (III), b. 1775 Mary Catherine Ann
Between 1780 and 1783, the entire extended Feland family moved to Lincoln Co. (still Virginia until 1792) Kentucky and settled on the Hanging Fork of Dix (Dick's) River. Thomas, Jr was the only one who was married before the move and Thomas Sr.'s other children married later in Kentucky.
There are a lot of good records from early Lincoln County.
If you could be a little more specific about what info you need, I may be able to help further.
Jack Johnson (6th great grandson of Thomas, Sr.) Tumbling Shoals, AR