There isn't any Isaac Adams in either the 1840, 1850, or 1860 Johnson Co. MO census. There is no Isaac Adams buried in any of the major Adams Cemeteries in Johnson Co. that I know of (Adams, Adams Memorial, Adams-Tackett).
There is an Isac Adams listed in the 1850 Wilkes Co. NC census age 54 living with a Cynthia age 40.Wilkes Co. marriage bonds show Isaac Adams and Susanna Walser bond date 30 July 1813 bondsman Eli Pettey, witness J.W. Pettey.They also show Isaac Adams and Sintha Roberds bond date 18 Oct 1817 bondsman John Roberds, witness W.W. Martin.Do you know the correct date of birth for Isaac and when Susan (Walser) Adams died?
Sons of Jacob that are confirmed to have gone to Johnson Co. MO are John, Spencer, and Abraham.Jacob Jr. is shown (LDS FamilySearch website) to have died in Lafayette Co. MO (Johnson was formed from Lafayette) but I haven't seen any confirmation of it.Pettis Co., just East of Johnson Co. is another possibility as most of these Adams settled in the Eastern part of Johnson Co. with some near the County line in Knob Knoster.
There were some Wilkes Co. Adams' that settled in Johnson Co. MO after 1850 that may be descended from Jacob's brother Spencer. That's Zacheriah B. Adams and Sarah Caroline (Cleveland) Adams and children.Their older children may have settled in Clay Co.
There is a grave in the Adams Memorial Cemetery for "Abbie Adams, 1846-1917, daughter of David and Susan" that I can't account for.Could that be your David Walker Adams?
I'd really appreciate if you could provide all the vital information you have on these Adams so that I could include them in my Adams database.Also, if your middle name indicates an Ellis family connection I'd love to hear about that too (My great grandmother was an Ellis).