Here are a few Marron marriages from Magheracloone which have the names of villages from rootsireland.ie/.
There are no listings for Magehracloone R C but you could try the nli R C registers at https://registers.nli.ie/
They have baptisms from 1836 to 1881
Date of Marriage: 09-Oct-1850
Parish / District: Magheracloone Church of Ireland County: Co. Monaghan
Husband Wife
Name: Alexander Shanks Martha Marron
Address: Carrickmacross, Co. Monaghan Monia
Denomination: [not Listed]
Occupation: pensioner 36 years
Age: 42 Years Widow
Status: Widower None Liste
Husband's Father Wife's Father
Name: John Shanks George Anderson
Address: [not Listed] [not Listed]
Denomination: Not Recorded Not Recorded
Occupation: farmer publican
Date of Marriage: 24-Nov-1862
Parish / District: Magheracloone Church of Ireland County: Co. Monaghan
Husband Wife
Name: Richard Baldwin Elizabeth Marron
Address: Dublin Ballyloughan, Magheracloone
Denomination: [not Listed]
Occupation: in business minor
Age: Aged 26 Spinster
Status: Bachelor None Listed
Date of Marriage: 04-Mar-1879
Parish / District: Magheracloone Church of Ireland County: Co. Monaghan
Husband Wife
Name: Henry Reburn Emily Marren
Address: Carrickmaclim, Magheross, Co. Monaghan Ballyloughan, Magheracloone
Denomination: [not Listed]
Occupation: farmer full age
Age: Full Age Spinster
Status: Bachelor None Liste
Husband's Father Wife's Father
Name: Henry Reburn Thomas Marren
There are 25 Marrons in Monaghan in the Tithe Applotments (free at http://titheapplotmentbooks.nationalarchives.ie/) from 1823 to 1829. Only 1, Thomas, is from Magheracloone Townland is Mayheracloony
You might want to try Griffiths Valuation 1848 to 64 and Irish Censuses
The earliest Irish Census which has Monaghan records is 1851 but there are no Marrons
Col