Okay, so - liners between 1820 and 1829 inclusive. Note that US gun counts are hard to get with certainty as they were often not armed for a full-on war - e.g. the North Carolina was pierced for 102, nominally a 74, and carried around 90-94 guns
US Navy - Liners
Independence (90) - commission until 1822, then in ordinary
Washington (90) - Ordinary for entire decade
Franklin (90) - Med until March 1820, Pacific 1821-24, Ordinary
Columbus (92) - Med 1820-21, Ordinary
Chippewa - unfinished, Great Lakes
New Orleans - unfinished, Great Lakes
Pennsylvania(140) - keel laid 1821, low budgets prevented finishing and launch until 1837
Delaware (74) - Ordinary 1820-8, finished 1828 and went to Med
Vermont (74) - Ready for launch 1825, Ordinary until 1848
New Hampshire (74) - Ready for launch 1825
Virginia (74) - Ready for launch 1825
New York (74) - never launched
Ohio (74?) - launched 1820, Ordinary
North Carolina (104) - launched 1820, commissioned 1824
Looks like to me that in a war situation they could activate a couple of the unfinished ships a year.
Spanish status hard to get. Will note any status change in the 1820s.
Spanish navy - liners
Guerrero (74)
America (68) BU 1823
Sobrerano (74)
San Justo (74) BU 1824
San Julian (60) BU 1830
San Francisco de Paula (74) BU 1823
Asia (64) Mutinied to Mexico 1825
Heroe (80)
Algeciras (80) stricken 1826
Neptuno (80) BU 1820
Fernando VII (74) Stricken 1823
Alejandro I (74) Stricken 1823
Numancia I (74) BU 1823
España (74) Stricken 1821
Velasco (74) Stricken 1821
Major change in Spanish power over the 1820s, trending down.
So what it looks like to me is that battlefleet wise the US will have the advantage later in the decade. By 1828 there's only four Spanish liners left and they're all quite old.
Earlier on the large number of Spanish liners gives them the whip hand as there's as few as three US liners in commission.