McGough, 22, is believed to be the Minor Leaguer going to Miami in the deal, according to MLB.com. The teams are expected to formally announce the deal's details later on Wednesday.
Eovaldi, a highly-regarded righty who made his Major League debut last summer, has split the 2012 season between Double-A Chattanooga and Los Angeles. In the Southern League, Eovaldi went 2-2 with a 3.09 ERA in nine outings before being promoted to the Majors following his start on May 26.
He's started 10 games for the Dodgers this season, going 1-6 with a 4.15 ERA and has filled in nicely for the injured Ted Lilly despite a lack of run support.
McGough was the Dodgers' fifth-round pick in the 2011 Draft out of Oregon and is 3-5 with a 3.99 ERA and five saves in 35 outings for Class A Advanced Rancho Cucamonga this season. He's struck out 48 in 47 1/3 innings, is holding batters to a .249 average and has allowed just three home runs in that span.
The righty made his Minor League debut last summer with Rookie-level Ogden and finished the season with Class A Great Lakes, going a combined 1-5 with a 2.77 ERA and 10 saves in 26 games.
Eovaldi had been scheduled to start on Friday for Los Angeles, and according to MLB.com, if the Dodgers are unable to acquire another starter by Friday -- perhaps Cubs veteran Ryan Dempster -- they might call up prospect Allen Webster from Double-A Chattanooga to make the start.
Webster, currently ranked as the Dodgers' No. 2 prospect, is 4-8 with a 4.06 ERA in 21 games (16 starts) for the Lookouts this season.
Ramirez, 28, is hitting .246 with 14 home runs and 47 RBIs in 92 games for Miami this season, while Choate, a 36-year-old side-arming reliever, owns a 2.49 ERA in 44 appearances.
The deal comes a day after the Marlins traded for former Tigers top prospect Jacob Turner, Minor League catcher Rob Brantly and left-handed prospect Brian Flynn on Monday in exchange for starter Anibal Sanchez and second baseman Omar Infante.