3. Allen:

"μ, 4.3, orange, and ε were Al Ashfār, the Eyebrows; but, singly, the Arabians designated μ as Al Rās al Asad al Shamāliyy, the Lion's Head towards the South, which, by abbreviation, has become Rasalas in modern lists; and sometimes, but very insufficiently, plain Alshemali.

Al Nasr al Din mentioned ε and μ as a whip's length apart, a common expression for measurement among the Arabs, here indicating a little more than 2º."

149.7 - 147.6 = 2.1 is indeed the difference in right ascension:

period 6
Ga3-22 Ga3-23 Ga3-24 (*148)
    Ras Elaset Australis (147.6)
period 7
Ga4-1 Ga4-2 Ga4-3 Ga4-4 (*152)
  Ras Elaset Borealis (149.7)    

But we ought to begin earlier, already with κ and λ:

"This [κ] was designated by Ulug Beg as Al Minhar al Asad, the Lion's Nose, still correct for it as laid down on the Heis Atlas, although now never used as a star-title." (Allen)

"Alterf [λ] is from Al Tarf, the name for the 7th manzil, which it formed with ξ Cancri.

The word has generally been rendered the Glance, i.e. of the Lion's eye, although on modern maps the star lies in the open mouth, where Ptolemy located it.

But it also had the secondary meaning of the Extremity, still more appropriate here, and so understood by Ideler." (Allen)

My thoughts as to the meaning of the 'eye' of the Lion have been presented in The Feelers when discussing manu kake in Ga3-1. The Lion is stretching out his tongue towards the Crab, and it thus becomes his extremity:

(Picure by Flamsteed)

Acubens 08h 58m 29.20s 08h 58.487m 136.0
κ Leonis 09h 24m 39.28s 09h 24.655m 142.6
λ Leonis 09h 31m 43.24s 09h 31.721m 144.4

The 10th hour:

  ν Cancri 5.45 24° 27′ N 09h 00m 137.0 545.0
  σ¹ Ursa Majoris 5.15 66° 52′ N 09h 04m 138.0 546.0
  κ Cancri 5.23 10° 40′ N 09h 05m 138.3 546.3

Alsuhail

λ Velorum 2.23 43° 14′ S 09h 06m 138.5 546.5
  σ² Ursa Majoris 4.80 67° 08′ N 09h 06m 138.6 546.6
  τ (2 stars) Ursa Majoris 4.67 63° 31′ N 09h 07m 138.7 546.7
  ξ Cancri 5.16 22° 03′ N 09h 07m 138.8 546.8

Miaplacidus

β Carinae 1.67 69° 31′ S 09h 13m 140.3 548.3

Tureis

ε Carinae 1.86 59° 03′ S 09h 15m 140.8 548.8

Al Minhar al Asad

κ Leonis 4.47 26° 11′ N 09h 22m 142.6 550.6

Alphard

α Hydrae 1.99 08° 26′ S 09h 25m 143.3 551.3

Alterf

λ Leonis 4.32 22° 58′ N 09h 29m 144.4 552.4

Ras Elaset Australis

ε Leonis 2.97 24° 00′ N 09h 43m 147.6 555.6

Ras Elaset Borealis

μ Leonis 3.88 26° 15′ N 09h 50m 149.7 557.7
period 4
Ga3-17 Ga3-18 Ga3-19 (*143)
Tureis (140.8) Al Minhar al Asad (142.6) Alphard (143.3)

period 4

Tureis

ε Carinae 1.86 59° 03′ S 09h 15m 140.8 548.8

Al Minhar al Asad

κ Leonis 4.47 26° 11′ N 09h 22m 142.6 550.6

Alphard

α Hydrae 1.99 08° 26′ S 09h 25m 143.3 551.3
period 5
Ga3-20 (80) Ga3-21
Alterf (144.4)  
period 6
Ga3-22 Ga3-23 Ga3-24 (*148)
    Ras Elaset Australis (147.6)
period 7
Ga4-1 Ga4-2 Ga4-3 Ga4-4 (*152)
  Ras Elaset Borealis (149.7)    

periods 5-7

Alterf

λ Leonis 4.32 22° 58′ N 09h 29m 144.4 552.4

Ras Elaset Australis

ε Leonis 2.97 24° 00′ N 09h 43m 147.6 555.6

Ras Elaset Borealis

μ Leonis 3.88 26° 15′ N 09h 50m 149.7 557.7