Information on the Find a Grave website for James states that he came to America in 1861. The only James Bowman whose name appears on a ship manifest in 1861 was born about 1821, and he came to America alone on the Monarch of the Sea. This may or may not be this James.
Neither James' nor Isabella's names appear on the 1856 Utah census. The first documentation to place them in Utah is their involvement with the Morrisite church in June 1862. Isabella, was killed during the Morrisite War 13 June 1862 at Kington Fort, Weber County, Utah.
In the Spring of 1863, James moved to Idaho.
Further research is needed to determine the name of the pioneer company that they traveled to Utah with.